In vivo tomographic imaging of deep seated cancer using fluorescence lifetime contrast

PubMed Central

Rice, William L.; Shcherbakova, Daria M; Verkusha, Vladislav V.; Kumar, Anand T.N.

2015-01-01

Preclinical cancer research would benefit from non-invasive imaging methods that allow tracking and visualization of early stage metastasis in vivo. While fluorescent proteins revolutionized intravital microscopy, two major challenges which still remain are tissue autofluorescence and hemoglobin absorption, which act to limit intravital optical techniques to large or subcutaneous tumors. Here we employ time-domain technology for the effective separation of tissue autofluorescence from extrinsic fluorophores, based on their distinct fluorescence lifetimes. Additionally, we employ cancer cells labelled with near infra-red fluorescent proteins (iRFP) to allow deep-tissue imaging. Our results demonstrate that time-domain imaging allows the detection of metastasis in deep-seated organs of living mice with a more than 20-fold increase in sensitivity compared to conventional continuous wave techniques. Furthermore, the distinct fluorescence lifetimes of each iRFP enables lifetime multiplexing of three different tumors, each expressing unique iRFP labels in the same animal. Fluorescence tomographic reconstructions reveal 3D distributions of iRFP720-expressing cancer cells in lungs and brain of live mice, allowing ready longitudinal monitoring of cancer cell fate with greater sensitivity than otherwise currently possible. PMID:25670171

Near-Infrared Fluorescence-Enhanced Optical Tomography

PubMed Central

2016-01-01

Fluorescence-enhanced optical imaging using near-infrared (NIR) light developed for in vivo molecular targeting and reporting of cancer provides promising opportunities for diagnostic imaging. The current state of the art of NIR fluorescence-enhanced optical tomography is reviewed in the context of the principle of fluorescence, the different measurement schemes employed, and the mathematical tools established to tomographically reconstruct the fluorescence optical properties in various tissue domains. Finally, we discuss the recent advances in forward modeling and distributed memory parallel computation to provide robust, accurate, and fast fluorescence-enhanced optical tomography. PMID:27803924

Near-Infrared Fluorescence-Enhanced Optical Tomography.

PubMed

Zhu, Banghe; Godavarty, Anuradha

2016-01-01

Fluorescence-enhanced optical imaging using near-infrared (NIR) light developed for in vivo molecular targeting and reporting of cancer provides promising opportunities for diagnostic imaging. The current state of the art of NIR fluorescence-enhanced optical tomography is reviewed in the context of the principle of fluorescence, the different measurement schemes employed, and the mathematical tools established to tomographically reconstruct the fluorescence optical properties in various tissue domains. Finally, we discuss the recent advances in forward modeling and distributed memory parallel computation to provide robust, accurate, and fast fluorescence-enhanced optical tomography.

Quantitative multiphoton imaging

NASA Astrophysics Data System (ADS)

König, Karsten; Weinigel, Martin; Breunig, Hans Georg; Uchugonova, Aisada

2014-02-01

Certified clinical multiphoton tomographs for label-free multidimensional high-resolution in vivo imaging have been introduced to the market several years ago. Novel tomographs include a flexible 360° scan head attached to a mechanooptical arm for autofluorescence and SHG imaging as well as a CARS module. Non-fluorescent lipids and water, mitochondrial fluorescent NAD(P)H, fluorescent elastin, keratin, and melanin as well as SHG-active collagen can be imaged in vivo with submicron resolution in human skin. Sensitive and rapid detectors allow single photon counting and the construction of 3D maps where the number of detected photons per voxel is depicted. Intratissue concentration profiles from endogenous as well exogenous substances can be generated when the number of detected photons can be correlated with the number of molecules with respect to binding and scattering behavior. Furthermore, the skin ageing index SAAID based on the ratio elastin/collagen as well as the epidermis depth based on the onset of SHG generation can be determined.

5D-intravital tomography as a novel tool for non-invasive in-vivo analysis of human skin

NASA Astrophysics Data System (ADS)

König, Karsten; Weinigel, Martin; Breunig, Hans G.; Gregory, Axel; Fischer, Peter; Kellner-Höfer, Marcel; Bückle, Rainer; Schwarz, Martin; Riemann, Iris; Stracke, Frank; Huck, Volker; Gorzelanny, Christian; Schneider, Stefan W.

2010-02-01

Some years ago, CE-marked clinical multiphoton systems for 3D imaging of human skin with subcellular resolution have been launched. These tomographs provide optical biopsies with submicron resolution based on two-photon excited autofluorescence (NAD(P)H, flavoproteins, keratin, elastin, melanin, porphyrins) and second harmonic generation by collagen. The 3D tomograph was now transferred into a 5D imaging system by the additional detection of the emission spectrum and the fluorescence lifetime based on spatially and spectrally resolved time-resolved single photon counting. The novel 5D intravital tomograph (5D-IVT) was employed for the early detection of atopic dermatitis and the analysis of treatment effects.

Fluorescence tomography using synchrotron radiation at the NSLS

NASA Astrophysics Data System (ADS)

Boisseau, P.; Grodzins, L.

1987-03-01

Fluorescence tomography utilizing focussed, tunable, monoenergetic X-rays from synchrotron light sources hold the promise of a non-invasive analytic tool for studying trace elements in specimens, particularly biological, at spatial resolutions of the order of micrometers. This note reports an early test at the National Synchrotron Light Source at Brookhaven National Laboratories in which fluorescence tomographic scans were successfully made of trace elements of iron and titanium in NBS standard glass and in a bee.

Clinical multiphoton FLIM tomography

NASA Astrophysics Data System (ADS)

König, Karsten

2012-03-01

This paper gives an overview on current clinical high resolution multiphoton fluorescence lifetime imaging in volunteers and patients. Fluorescence lifetime imaging (FLIM) in Life Sciences was introduced in Jena/Germany in 1988/89 based on a ZEISS confocal picosecond dye laser scanning microscope equipped with a single photon counting unit. The porphyrin distribution in living cells and living tumor-bearing mice was studied with high spatial, temporal, and spectral resolution. Ten years later, time-gated cameras were employed to detect dental caries in volunteers based on one-photon excitation of autofluorescent bacteria with long fluorescence lifetimes. Nowadays, one-photon FLIM based on picosecond VIS laser diodes are used to study ocular diseases in humans. Already one decade ago, first clinical twophoton FLIM images in humans were taken with the certified clinical multiphoton femtosecond laser tomograph DermaInspectTM. Multiphoton tomographs with FLIM modules are now operating in hospitals at Brisbane, Tokyo, Berlin, Paris, London, Modena and other European cities. Multiple FLIM detectors allow spectral FLIM with a temporal resolution down to 20 ps (MCP) / 250 ps (PMT) and a spectral resolution of 10 nm. Major FLIM applications include the detection of intradermal sunscreen and tattoo nanoparticles, the detection of different melanin types, the early diagnosis of dermatitis and malignant melanoma, as well as the measurement of therapeutic effects in pateints suffering from dermatitis. So far, more than 1,000 patients and volunteers have been investigated with the clinical multiphoton FLIM tomographs DermaInspectTM and MPTflexTM.

In vivo fluorescence lifetime optical projection tomography

PubMed Central

McGinty, James; Taylor, Harriet B.; Chen, Lingling; Bugeon, Laurence; Lamb, Jonathan R.; Dallman, Margaret J.; French, Paul M. W.

2011-01-01

We demonstrate the application of fluorescence lifetime optical projection tomography (FLIM-OPT) to in vivo imaging of lysC:GFP transgenic zebrafish embryos (Danio rerio). This method has been applied to unambiguously distinguish between the fluorescent protein (GFP) signal in myeloid cells from background autofluorescence based on the fluorescence lifetime. The combination of FLIM, an inherently ratiometric method, in conjunction with OPT results in a quantitative 3-D tomographic technique that could be used as a robust method for in vivo biological and pharmaceutical research, for example as a readout of Förster resonance energy transfer based interactions. PMID:21559145

Spectral unmixing of multi-color tissue specific in vivo fluorescence in mice

NASA Astrophysics Data System (ADS)

Zacharakis, Giannis; Favicchio, Rosy; Garofalakis, Anikitos; Psycharakis, Stylianos; Mamalaki, Clio; Ripoll, Jorge

2007-07-01

Fluorescence Molecular Tomography (FMT) has emerged as a powerful tool for monitoring biological functions in vivo in small animals. It provides the means to determine volumetric images of fluorescent protein concentration by applying the principles of diffuse optical tomography. Using different probes tagged to different proteins or cells, different biological functions and pathways can be simultaneously imaged in the same subject. In this work we present a spectral unmixing algorithm capable of separating signal from different probes when combined with the tomographic imaging modality. We show results of two-color imaging when the algorithm is applied to separate fluorescence activity originating from phantoms containing two different fluorophores, namely CFSE and SNARF, with well separated emission spectra, as well as Dsred- and GFP-fused cells in F5-b10 transgenic mice in vivo. The same algorithm can furthermore be applied to tissue-specific spectroscopy data. Spectral analysis of a variety of organs from control, DsRed and GFP F5/B10 transgenic mice showed that fluorophore detection by optical systems is highly tissue-dependent. Spectral data collected from different organs can provide useful insight into experimental parameter optimisation (choice of filters, fluorophores, excitation wavelengths) and spectral unmixing can be applied to measure the tissue-dependency, thereby taking into account localized fluorophore efficiency. Summed up, tissue spectral unmixing can be used as criteria in choosing the most appropriate tissue targets as well as fluorescent markers for specific applications.

Photoacoustic imaging of fluorophores using pump-probe excitation

PubMed Central

Märk, Julia; Schmitt, Franz-Josef; Theiss, Christoph; Dortay, Hakan; Friedrich, Thomas; Laufer, Jan

2015-01-01

A pump-probe technique for the detection of fluorophores in tomographic PA images is introduced. It is based on inducing stimulated emission in fluorescent molecules, which in turn modulates the amount of thermalized energy, and hence the PA signal amplitude. A theoretical model of the PA signal generation in fluorophores is presented and experimentally validated on cuvette measurements made in solutions of Rhodamine 6G, a fluorophore of known optical and molecular properties. The application of this technique to deep tissue tomographic PA imaging is demonstrated by determining the spatial distribution of a near-infrared fluorophore in a tissue phantom. PMID:26203378

Current developments in clinical multiphoton tomography

NASA Astrophysics Data System (ADS)

König, Karsten; Weinigel, Martin; Breunig, Hans Georg; Gregory, Axel; Fischer, Peter; Kellner-Höfer, Marcel; Bückle, Rainer

2010-02-01

Two-photon microscopy has been introduced in 1990 [1]. 13 years later, CE-marked clinical multiphoton systems for 3D imaging of human skin with subcellular resolution have been launched by the JenLab company with the tomograph DermaInspectTM. In 2010, the second generation of clinical multiphoton tomographs was introduced. The novel mobile multiphoton tomograph MPTflexTM, equipped with a flexible articulated optical arm, provides an increased flexibility and accessibility especially for clinical and cosmetical examinations. The multiphoton excitation of fluorescent biomolecules like NAD(P)H, flavins, porphyrins, elastin, and melanin as well as the second harmonic generation of collagen is induced by picojoule femtosecond laser pulses from an tunable turn-key near infrared laser system. The ability for rapid highquality image acquisition, the user-friendly operation of the system, and the compact and flexible design qualifies this system to be used for melanoma detection, diagnostics of dermatological disorders, cosmetic research, and skin aging measurements as well as in situ drug monitoring and animal research. So far, more than 1,000 patients and volunteers have been investigated with the multiphoton tomographs in Europe, Asia, and Australia.

In vivo fluorescence lifetime tomography of a FRET probe expressed in mouse

PubMed Central

McGinty, James; Stuckey, Daniel W.; Soloviev, Vadim Y.; Laine, Romain; Wylezinska-Arridge, Marzena; Wells, Dominic J.; Arridge, Simon R.; French, Paul M. W.; Hajnal, Joseph V.; Sardini, Alessandro

2011-01-01

Förster resonance energy transfer (FRET) is a powerful biological tool for reading out cell signaling processes. In vivo use of FRET is challenging because of the scattering properties of bulk tissue. By combining diffuse fluorescence tomography with fluorescence lifetime imaging (FLIM), implemented using wide-field time-gated detection of fluorescence excited by ultrashort laser pulses in a tomographic imaging system and applying inverse scattering algorithms, we can reconstruct the three dimensional spatial localization of fluorescence quantum efficiency and lifetime. We demonstrate in vivo spatial mapping of FRET between genetically expressed fluorescent proteins in live mice read out using FLIM. Following transfection by electroporation, mouse hind leg muscles were imaged in vivo and the emission of free donor (eGFP) in the presence of free acceptor (mCherry) could be clearly distinguished from the fluorescence of the donor when directly linked to the acceptor in a tandem (eGFP-mCherry) FRET construct. PMID:21750768

Performance of different reflectance and diffuse optical imaging tomographic approaches in fluorescence molecular imaging of small animals

NASA Astrophysics Data System (ADS)

Dinten, Jean-Marc; Petié, Philippe; da Silva, Anabela; Boutet, Jérôme; Koenig, Anne; Hervé, Lionel; Berger, Michel; Laidevant, Aurélie; Rizo, Philippe

2006-03-01

Optical imaging of fluorescent probes is an essential tool for investigation of molecular events in small animals for drug developments. In order to get localization and quantification information of fluorescent labels, CEA-LETI has developed efficient approaches in classical reflectance imaging as well as in diffuse optical tomographic imaging with continuous and temporal signals. This paper presents an overview of the different approaches investigated and their performances. High quality fluorescence reflectance imaging is obtained thanks to the development of an original "multiple wavelengths" system. The uniformity of the excitation light surface area is better than 15%. Combined with the use of adapted fluorescent probes, this system enables an accurate detection of pathological tissues, such as nodules, beneath the animal's observed area. Performances for the detection of ovarian nodules on a nude mouse are shown. In order to investigate deeper inside animals and get 3D localization, diffuse optical tomography systems are being developed for both slab and cylindrical geometries. For these two geometries, our reconstruction algorithms are based on analytical expression of light diffusion. Thanks to an accurate introduction of light/matter interaction process in the algorithms, high quality reconstructions of tumors in mice have been obtained. Reconstruction of lung tumors on mice are presented. By the use of temporal diffuse optical imaging, localization and quantification performances can be improved at the price of a more sophisticated acquisition system and more elaborate information processing methods. Such a system based on a pulsed laser diode and a time correlated single photon counting system has been set up. Performances of this system for localization and quantification of fluorescent probes are presented.

Dynamic Imaging of Mouse Embryos and Cardiodynamics in Static Culture.

PubMed

Lopez, Andrew L; Larina, Irina V

2018-01-01

The heart is a dynamic organ that quickly undergoes morphological and mechanical changes through early embryonic development. Characterizing these early moments is important for our understanding of proper embryonic development and the treatment of heart disease. Traditionally, tomographic imaging modalities and fluorescence-based microscopy are excellent approaches to visualize structural features and gene expression patterns, respectively, and connect aberrant gene programs to pathological phenotypes. However, these approaches usually require static samples or fluorescent markers, which can limit how much information we can derive from the dynamic and mechanical changes that regulate heart development. Optical coherence tomography (OCT) is unique in this circumstance because it allows for the acquisition of three-dimensional structural and four-dimensional (3D + time) functional images of living mouse embryos without fixation or contrast reagents. In this chapter, we focus on how OCT can visualize heart morphology at different stages of development and provide cardiodynamic information to reveal mechanical properties of the developing heart.

Fluorescence tomography characterization for sub-surface imaging with protoporphyrin IX

PubMed Central

Kepshire, Dax; Davis, Scott C.; Dehghani, Hamid; Paulsen, Keith D.; Pogue, Brian W.

2009-01-01

Optical imaging of fluorescent objects embedded in a tissue simulating medium was characterized using non-contact based approaches to fluorescence remittance imaging (FRI) and sub-surface fluorescence diffuse optical tomography (FDOT). Using Protoporphyrin IX as a fluorescent agent, experiments were performed on tissue phantoms comprised of typical in-vivo tumor to normal tissue contrast ratios, ranging from 3.5:1 up to 10:1. It was found that tomographic imaging was able to recover interior inclusions with high contrast relative to the background; however, simple planar fluorescence imaging provided a superior contrast to noise ratio. Overall, FRI performed optimally when the object was located on or close to the surface and, perhaps most importantly, FDOT was able to recover specific depth information about the location of embedded regions. The results indicate that an optimal system for localizing embedded fluorescent regions should combine fluorescence reflectance imaging for high sensitivity and sub-surface tomography for depth detection, thereby allowing more accurate localization in all three directions within the tissue. PMID:18545571

A study of MRI-guided diffuse fluorescence molecular tomography for monitoring PDT effects in pancreas cancer

NASA Astrophysics Data System (ADS)

Samkoe, Kimberley S.; Davis, Scott C.; Srinivasan, Subhadra; O'Hara, Julia A.; Hasan, Tayyaba; Pogue, Brian W.

2009-06-01

Over the last several decades little progress has been made in the therapy and treatment monitoring of pancreas adenocarcinoma, a devastating and aggressive form of cancer that has a 5-year patient survival rate of 3%. Currently, investigations for the use of interstitial Verteporfin photodynamic therapy (PDT) are being undertaken in both orthotopic xenograft mouse models and in human clinical trials. In the mouse models, magnetic resonance (MR) imaging has been used as a measure of surrogate response to Verteporfin PDT; however, MR imaging alone lacks the molecular information required to assess the metabolic function and growth rates of the tumor immediately after treatment. We propose the implementation of MR-guided fluorescence tomography in conjunction with a fluorescently labeled (IR-Dye 800 CW, LI-COR) epidermal growth factor (EGF) as a molecular measure of surrogate response. To demonstrate the effectiveness of MR-guided diffuse fluorescence tomography for molecular imaging, we have used the AsPC-1 (+EGFR) human pancreatic adenocarcinoma in an orthotopic mouse model. EGF IRDye 800CW was injected 48 hours prior to imaging. MR image sequences were collected simultaneously with the fluorescence data using a MR-coupled diffuse optical tomography system. Image reconstruction was performed multiple times with varying abdominal organ segmentation in order to obtain a optimal tomographic image. It is shown that diffuse fluorescence tomography of the orthotopic pancreas model is feasible, with consideration of confounding fluorescence signals from the multiple organs and tissues surrounding the pancreas. MR-guided diffuse fluorescence tomography will be used to monitor EGF response after photodynamic therapy. Additionally, it provide the opportunity to individualize subsequent therapies based on response to PDT as well as to evaluate the success of combination therapies, such as PDT with chemotherapy, antibody therapy or even radiation.

Rapid tomographic reconstruction based on machine learning for time-resolved combustion diagnostics

NASA Astrophysics Data System (ADS)

Yu, Tao; Cai, Weiwei; Liu, Yingzheng

2018-04-01

Optical tomography has attracted surged research efforts recently due to the progress in both the imaging concepts and the sensor and laser technologies. The high spatial and temporal resolutions achievable by these methods provide unprecedented opportunity for diagnosis of complicated turbulent combustion. However, due to the high data throughput and the inefficiency of the prevailing iterative methods, the tomographic reconstructions which are typically conducted off-line are computationally formidable. In this work, we propose an efficient inversion method based on a machine learning algorithm, which can extract useful information from the previous reconstructions and build efficient neural networks to serve as a surrogate model to rapidly predict the reconstructions. Extreme learning machine is cited here as an example for demonstrative purpose simply due to its ease of implementation, fast learning speed, and good generalization performance. Extensive numerical studies were performed, and the results show that the new method can dramatically reduce the computational time compared with the classical iterative methods. This technique is expected to be an alternative to existing methods when sufficient training data are available. Although this work is discussed under the context of tomographic absorption spectroscopy, we expect it to be useful also to other high speed tomographic modalities such as volumetric laser-induced fluorescence and tomographic laser-induced incandescence which have been demonstrated for combustion diagnostics.

Rapid tomographic reconstruction based on machine learning for time-resolved combustion diagnostics.

PubMed

Yu, Tao; Cai, Weiwei; Liu, Yingzheng

2018-04-01

Optical tomography has attracted surged research efforts recently due to the progress in both the imaging concepts and the sensor and laser technologies. The high spatial and temporal resolutions achievable by these methods provide unprecedented opportunity for diagnosis of complicated turbulent combustion. However, due to the high data throughput and the inefficiency of the prevailing iterative methods, the tomographic reconstructions which are typically conducted off-line are computationally formidable. In this work, we propose an efficient inversion method based on a machine learning algorithm, which can extract useful information from the previous reconstructions and build efficient neural networks to serve as a surrogate model to rapidly predict the reconstructions. Extreme learning machine is cited here as an example for demonstrative purpose simply due to its ease of implementation, fast learning speed, and good generalization performance. Extensive numerical studies were performed, and the results show that the new method can dramatically reduce the computational time compared with the classical iterative methods. This technique is expected to be an alternative to existing methods when sufficient training data are available. Although this work is discussed under the context of tomographic absorption spectroscopy, we expect it to be useful also to other high speed tomographic modalities such as volumetric laser-induced fluorescence and tomographic laser-induced incandescence which have been demonstrated for combustion diagnostics.

A Dual Modality System for Simultaneous Fluorescence and Positron Emission Tomography Imaging of Small Animals

NASA Astrophysics Data System (ADS)

Liu, Shuangquan; Zhang, Bin; Wang, Xin; Li, Lin; Chen, Yan; Liu, Xin; Liu, Fei; Shan, Baoci; Bai, Jing

2011-02-01

A dual-modality imaging system for simultaneous fluorescence molecular tomography (FMT) and positron emission tomography (PET) of small animals has been developed. The system consists of a noncontact 360°-projection FMT module and a flat panel detector pair based PET module, which are mounted orthogonally for the sake of eliminating cross interference. The FMT images and PET data are simultaneously acquired by employing dynamic sampling mode. Phantom experiments, in which the localization and range of radioactive and fluorescence probes are exactly indicated, have been carried out to verify the feasibility of the system. An experimental tumor-bearing mouse is also scanned using the dual-modality simultaneous imaging system, the preliminary fluorescence tomographic images and PET images demonstrate the in vivo performance of the presented dual-modality system.

Fluorescent scanning x-ray tomography with synchrotron radiation

NASA Astrophysics Data System (ADS)

Takeda, Tohoru; Maeda, Toshikazu; Yuasa, Tetsuya; Akatsuka, Takao; Ito, Tatsuo; Kishi, Kenichi; Wu, Jin; Kazama, Masahiro; Hyodo, Kazuyuki; Itai, Yuji

1995-02-01

Fluorescent scanning (FS) x-ray tomography was developed to detect nonradioactive tracer materials (iodine and gadolinium) in a living object. FS x-ray tomography consists of a silicon (111) channel cut monochromator, an x-ray shutter, an x-ray slit system and a collimator for detection, a scanning table for the target organ, and an x-ray detector with pure germanium. The minimal detectable dose of iodine in this experiment was 100 ng in a volume of 2 mm3 and a linear relationship was shown between the photon counts of a fluorescent x ray and the concentration of iodine contrast material. A FS x-ray tomographic image was clearly obtained with a phantom.

Two-photon autofluorescence/FLIM/SHG endoscopy to study the oral cavity and wound healing in humans (Conference Presentation)

NASA Astrophysics Data System (ADS)

König, Karsten

2016-03-01

Monitoring the oral cavity noninvasively with superior 3D resolution is realized by clinical multiphoton tomography and high NA two-photon endoscopy without the need of additional contrast agents. The technology behind this investigation is based on nonlinear optical contrast of the multiphoton tomograph MPTflex®. Furthermore, the miniaturized GRIN endoscope was used to realize more accessibility for more demanding wound conditions in skin. The MPTflex® distinguishes autofluorescence (AF) signals from second harmonic generation (SHG) signals simultaneously. Fluorescence lifetime imaging (FLIM) based on time correlated single photon counting (TCSPC) technology offers additional information on the functional level of the intratissue fluorophores, their binding status, and the contribution of SHG signals in chronic wounds.

Fluorescence and diffusive wave diffraction tomographic probes in turbid media

NASA Astrophysics Data System (ADS)

Li, Xingde

1998-10-01

Light transport over long distances in tissue-like highly scattering media is well approximated as a diffusive process. Diffusing photons can be used to detect, localize and characterize non-invasively optical inhomogeneities such as tumors and hematomas embedded in thick biological tissue. Most of the contrast relies on the endogenous optical property differences between the inhomogeneities and the surrounding media. Recently exogenous fluorescent contrast agents have been considered as a means to enhance the sensitivity and specificity for tumor detection. In the first part of the thesis (Chapter 2 and 3), a theoretical basis is established for modeling the transport, of fluorescent photons in highly scattering media. Fluorescent Diffuse Photon Density Waves (FDPDW) are used to describe the transport of fluorescent photons. A detailed analysis based upon a practical signal-to-noise model was used to access the utility of the fluorescent method. The analysis reveals that a small heterogeneity, embedded in deep tissue-like turbid media with biologically relevant parameters, and with a practically achievable 5-fold fluorophore concentration contrast, can be detected and localized when its radius is greater than 0.2 cm, and can be characterized when its radius is greater than 0.7 cm. In vivo and preliminary clinical studies demonstrate the feasibility of using FDPDW's for tumor diagnosis. Optical imaging with diffusing photons is challenging. Many of the imaging algorithms developed so far are either fundamentally incorrect as in the case of back- projection approach, or require a huge amount of computational resources and CPU time. In the second part of the thesis (Chapter 4), a fast, K-space diffraction tomographic imaging algorithm based upon spatial angular spectrum analysis is derived and applied. Absolute optical properties of thin inhomogeneities and relative optical properties of spatially extended inhomogeneities are reconstructed within a sub-second time scale. Phantom experiments have demonstrated the power of the K-space algorithm and preliminary clinical investigations have exhibited its potential for real time optical diagnosis and imaging of breast cancer.

Lateral resolution testing of a novel developed confocal microscopic imaging system

NASA Astrophysics Data System (ADS)

Zhang, Xin; Zhang, Yunhai; Chang, Jian; Huang, Wei; Xue, Xiaojun; Xiao, Yun

2015-10-01

Laser scanning confocal microscope has been widely used in biology, medicine and material science owing to its advantages of high resolution and tomographic imaging. Based on a set of confirmatory experiments and system design, a novel confocal microscopic imaging system is developed. The system is composed of a conventional fluorescence microscope and a confocal scanning unit. In the scanning unit a laser beam coupling module provides four different wavelengths 405nm 488nm 561nm and 638nm which can excite a variety of dyes. The system works in spot-to-spot scanning mode with a two-dimensional galvanometer. A 50 microns pinhole is used to guarantee that stray light is blocked and only the fluorescence signal from the focal point can be received . The three-channel spectral splitter is used to perform fluorescence imaging at three different working wavelengths simultaneously. The rat kidney tissue slice is imaged using the developed confocal microscopic imaging system. Nucleues labeled by DAPI and kidney spherule curved pipe labeled by Alexa Fluor 488 can be imaged clearly and respectively, realizing the distinction between the different components of mouse kidney tissue. The three-dimensional tomographic imaging of mouse kidney tissue is reconstructed by several two-dimensional images obtained in different depths. At last the resolution of the confocal microscopic imaging system is tested quantitatively. The experimental result shows that the system can achieve lateral resolution priority to 230nm.

Clinical coherent anti-Stokes Raman scattering and multiphoton tomography of human skin with a femtosecond laser and photonic crystal fiber

NASA Astrophysics Data System (ADS)

Breunig, Hans Georg; Weinigel, Martin; Bückle, Rainer; Kellner-Höfer, Marcel; Lademann, Jürgen; Darvin, Maxim E.; Sterry, Wolfram; König, Karsten

2013-02-01

We report on in vivo coherent anti-Stokes Raman scattering spectroscopy (CARS), two-photon fluorescence and second-harmonic-generation imaging on human skin with a novel multimodal clinical CARS/multiphoton tomograph. CARS imaging is realized by a combination of femtosecond pulses with broadband continuum pulses generated by a photonic crystal fiber. The images reveal the microscopic distribution of (i) non-fluorescent lipids, (ii) endogenous fluorophores and (iii) the collagen network inside the human skin in vivo with subcellular resolution. Examples of healthy as well as cancer-affected skin are presented.

Spatial photosensitizer fluorescence emission predictive analysis for photodynamic therapy monitoring applied to a skin disease

NASA Astrophysics Data System (ADS)

Salas-García, Irene; Fanjul-Vélez, Félix; Arce-Diego, José Luis

2012-03-01

The development of Photodynamic Therapy (PDT) predictive models has become a valuable tool for an optimal treatment planning, monitoring and dosimetry adjustment. A few attempts have achieved a quite complete characterization of the complex photochemical and photophysical processes involved, even taking into account superficial fluorescence in the target tissue. The present work is devoted to the application of a predictive PDT model to obtain fluorescence tomography information during PDT when applied to a skin disease. The model takes into account the optical radiation distribution, a non-homogeneous topical photosensitizer distribution, the time dependent photochemical interaction and the photosensitizer fluorescence emission. The results show the spatial evolution of the photosensitizer fluorescence emission and the amount of singlet oxygen produced during PDT. The depth dependent photosensitizer fluorescence emission obtained is essential to estimate the spatial photosensitizer concentration and its degradation due to photobleaching. As a consequence the proposed approach could be used to predict the photosensitizer fluorescence tomographic measurements during PDT. The singlet oxygen prediction could also be employed as a valuable tool to predict the short term treatment outcome.

Tomographic measurement of joint photon statistics of the twin-beam quantum state

PubMed

Vasilyev; Choi; Kumar; D'Ariano

2000-03-13

We report the first measurement of the joint photon-number probability distribution for a two-mode quantum state created by a nondegenerate optical parametric amplifier. The measured distributions exhibit up to 1.9 dB of quantum correlation between the signal and idler photon numbers, whereas the marginal distributions are thermal as expected for parametric fluorescence.

Tissue diagnosis by means of endogenous fluorophores

NASA Astrophysics Data System (ADS)

Lohmann, Wolfgang; Dreyer, Thomas; Nilles, M.; Bohle, Rainer M.; Schill, Wolf-Bernhard; Glanz, Hiltrud; Fryen, Andreas; Horn, Gisela; Pollich, Beate

1995-01-01

In vitro or in situ single spot or area excitation of human tissue with either 337 nm or 365 nm results in a fluorescence spectrum at about 470 nm. Since in most tissue samples the spectra obtained look alike and differ in intensity only, the 2D tomographical distribution of the fluorescence intensity was also investigated. It could be shown that the fluorescence images of unfixed and unstained cryosections match the histological images (HE stained cryosections). They exhibit a fluorescence pattern unique for the different types of diseases investigated (basalioma, melanoma, nevi, psoriasis, seborrheic keratosis). Additional information can be obtained by elastica van Gieson stained images and by illuminating the HE stained cryosections with 365 nm. Since the cryosections can be prepared and evaluated in less than 5 minutes, this technique might be used as a fast cut technique for determining e.g. the diagnosis of a biopsy sample, also during surgery.

Comparative analysis of fluorescent angiography, computed tomographic angiography and magnetic resonance angiography for planning autologous breast reconstruction

PubMed Central

Chae, Michael P.; Hunter-Smith, David J.

2015-01-01

Background The high incidence of breast cancer and growing number of breast cancer patients undergoing mastectomy has led to breast reconstruction becoming an important part of holistic treatment for these patients. In planning autologous reconstructions, preoperative assessment of donor site microvascular anatomy with advanced imaging modalities has assisted in the appropriate selection of flap donor site, individual perforators, and lead to an overall improvement in flap outcomes. In this review, we compare the accuracy of fluorescent angiography, computed tomographic angiography (CTA), and magnetic resonance angiography (MRA) and their impact on clinical outcomes. Methods A review of the published English literature dating from 1950 to 2015 using databases, such as PubMed, Medline, Web of Science, and EMBASE was undertaken. Results Fluorescent angiography is technically limited by its inability to evaluate deep-lying perforators and hence, it has a minimal role in the preoperative setting. However, it may be useful intraoperatively in evaluating microvascular anastomotic patency and the mastectomy skin perfusion. CTA is currently widely considered the standard, due to its high accuracy and reliability. Multiple studies have demonstrated its ability to improve clinical outcomes, such as operative length and flap complications. However, concerns surrounding exposure to radiation and nephrotoxic contrast agents exist. MRA has been explored, however despite recent advances, the image quality of MRA is considered inferior to CTA. Conclusions Preoperative imaging is an essential component in planning autologous breast reconstruction. Fluorescent angiography presents minimal role as a preoperative imaging modality, but may be a useful intraoperative adjunct to assess the anastomosis and the mastectomy skin perfusion. Currently, CTA is the gold standard preoperatively. MRA has a role, particularly for women of younger age, iodine allergy, and renal impairment. PMID:26005648

DOE Office of Scientific and Technical Information (OSTI.GOV)

Di, Zichao; Leyffer, Sven; Wild, Stefan M.

Fluorescence tomographic reconstruction, based on the detection of photons coming from fluorescent emission, can be used for revealing the internal elemental composition of a sample. On the other hand, conventional X-ray transmission tomography can be used for reconstructing the spatial distribution of the absorption coefficient inside a sample. In this work, we integrate both X-ray fluorescence and X-ray transmission data modalities and formulate a nonlinear optimization-based approach for reconstruction of the elemental composition of a given object. This model provides a simultaneous reconstruction of both the quantitative spatial distribution of all elements and the absorption effect in the sample. Mathematicallymore » speaking, we show that compared with the single-modality inversion (i.e., the X-ray transmission or fluorescence alone), the joint inversion provides a better-posed problem, which implies a better recovery. Therefore, the challenges in X-ray fluorescence tomography arising mainly from the effects of self-absorption in the sample are partially mitigated. The use of this technique is demonstrated on the reconstruction of several synthetic samples.« less

Multiphoton tomography of intratissue tattoo nanoparticles

NASA Astrophysics Data System (ADS)

König, Karsten

2012-02-01

Most of today's intratissue tattoo pigments are unknown nanoparticles. So far, there was no real control of their use due to the absence of regulations. Some of the tattoo pigments contain carcinogenic amines e.g. azo pigment Red 22. Nowadays, the European Union starts to control the administration of tattoo pigments. There is an interest to obtain information on the intratissue distribution, their interaction with living cells and the extracellular matrix, and the mechanisms behind laser tattoo removal. Multiphoton tomographs are novel biosafety and imaging tools that can provide such information non-invasively and without further labeling. When using the spectral FLIM module, spatially-resolved emission spectra, excitation spectra, and fluorescence lifetimes can pr provided. Multiphoton tomographs are used by all major cosmetic comapanies to test the biosafety of sunscreen nanoparticles.

Correlative Fluorescence and Electron Microscopy in 3D-Scanning Electron Microscope Perspective.

PubMed

Franks, Jonathan; Wallace, Callen T; Shibata, Masateru; Suga, Mitsuo; Erdman, Natasha; Stolz, Donna B; Watkins, Simon C

2017-04-03

The ability to correlate fluorescence microscopy (FM) and electron microscopy (EM) data obtained on biological (cell and tissue) specimens is essential to bridge the resolution gap between the data obtained by these different imaging techniques. In the past such correlations were limited to either EM navigation in two dimensions to the locations previously highlighted by fluorescence markers, or subsequent high-resolution acquisition of tomographic information using a TEM. We present a novel approach whereby a sample previously investigated by FM is embedded and subjected to sequential mechanical polishing and backscatter imaging by scanning electron microscope. The resulting three dimensional EM tomogram of the sample can be directly correlated to the FM data. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley & Sons, Inc.

Optical skin biopsies by clinical CARS and multiphoton fluorescence/SHG tomography

NASA Astrophysics Data System (ADS)

König, K.; Breunig, H. G.; Bückle, R.; Kellner-Höfer, M.; Weinigel, M.; Büttner, E.; Sterry, W.; Lademann, J.

2011-06-01

The ultimate challenge for early diagnostics is label-free high-resolution intratissue imaging without taking physical biopsies. A novel hybrid femtosecond laser tomograph provides in vivo optical biopsies of human skin based on non-linear excitation of autofluorescence and the detection of lipids and water by CARS. Applications include skin cancer detection, biosafety tests of intradermal nanoparticles, and the testing of anti-aging products.

Center-of-Mass Tomography and Wigner Function for Multimode Photon States

NASA Astrophysics Data System (ADS)

Dudinets, Ivan V.; Man'ko, Vladimir I.

2018-06-01

Tomographic probability representation of multimode electromagnetic field states in the scheme of center-of-mass tomography is reviewed. Both connection of the field state Wigner function and observable Weyl symbols with the center-of-mass tomograms as well as connection of the Grönewold kernel with the center-of-mass tomographic kernel determining the noncommutative product of the tomograms are obtained. The dual center-of-mass tomogram of the photon states are constructed and the dual tomographic kernel is obtained. The models of other generalized center-of-mass tomographies are discussed. Example of two-mode even and odd Schrödinger cat states is presented in details.

Chamber dimensions and functional assessment with coronary computed tomographic angiography as compared to echocardiography using American Society of Echocardiography guidelines

PubMed Central

Rose, Michael; Rubal, Bernard; Hulten, Edward; Slim, Jennifer N; Steel, Kevin; Furgerson, James L; Villines, Todd C

2014-01-01

Background: The correlation between normal cardiac chamber linear dimensions measured during retrospective coronary computed tomographic angiography as compared to transthoracic echocardiography using the American Society of Echocardiography guidelines is not well established. Methods: We performed a review from January 2005 to July 2011 to identify subjects with retrospective electrocardiogram-gated coronary computed tomographic angiography scans for chest pain and transthoracic echocardiography with normal cardiac structures performed within 90 days. Dimensions were manually calculated in both imaging modalities in accordance with the American Society of Echocardiography published guidelines. Left ventricular ejection fraction was calculated on echocardiography manually using the Simpson’s formula and by coronary computed tomographic angiography using the end-systolic and end-diastolic volumes. Results: We reviewed 532 studies, rejected 412 and had 120 cases for review with a median time between studies of 7 days (interquartile range (IQR25,75) = 0–22 days) with no correlation between the measurements made by coronary computed tomographic angiography and transthoracic echocardiography using Bland–Altman analysis. We generated coronary computed tomographic angiography cardiac dimension reference ranges for both genders for our population. Conclusion: Our findings represent a step towards generating cardiac chamber dimensions’ reference ranges for coronary computed tomographic angiography as compared to transthoracic echocardiography in patients with normal cardiac morphology and function using the American Society of Echocardiography guideline measurements that are commonly used by cardiologists. PMID:26770706

Lensless Tomographic Imaging of Near Surface Structures of Frozen Hydrated Malaria-Infected Human Erythrocytes by Coherent X-Ray Diffraction Microscopy.

PubMed

Frank, Viktoria; Chushkin, Yuriy; Fröhlich, Benjamin; Abuillan, Wasim; Rieger, Harden; Becker, Alexandra S; Yamamoto, Akihisa; Rossetti, Fernanda F; Kaufmann, Stefan; Lanzer, Michael; Zontone, Federico; Tanaka, Motomu

2017-10-26

Lensless, coherent X-ray diffraction microscopy has been drawing considerable attentions for tomographic imaging of whole human cells. In this study, we performed cryogenic coherent X-ray diffraction imaging of human erythrocytes with and without malaria infection. To shed light on structural features near the surface, "ghost cells" were prepared by the removal of cytoplasm. From two-dimensional images, we found that the surface of erythrocytes after 32 h of infection became much rougher compared to that of healthy, uninfected erythrocytes. The Gaussian roughness of an infected erythrocyte surface (69 nm) is about two times larger than that of an uninfected one (31 nm), reflecting the formation of protein knobs on infected erythrocyte surfaces. Three-dimensional tomography further enables to obtain images of the whole cells with no remarkable radiation damage, whose accuracy was estimated using phase retrieval transfer functions to be as good as 64 nm for uninfected and 80 nm for infected erythrocytes, respectively. Future improvements in phase retrieval algorithm, increase in degree of coherence, and higher flux in combination with complementary X-ray fluorescence are necessary to gain both structural and chemical details of mesoscopic architectures, such as cytoskeletons, membraneous structures, and protein complexes, in frozen hydrated human cells, especially under diseased states.

Plenoptic projection fluorescence tomography.

PubMed

Iglesias, Ignacio; Ripoll, Jorge

2014-09-22

A new method to obtain the three-dimensional localization of fluorochrome distributions in micrometric samples is presented. It uses a microlens array coupled to the image port of a standard microscope to obtain tomographic data by a filtered back-projection algorithm. Scanning of the microlens array is proposed to obtain a dense data set for reconstruction. Simulation and experimental results are shown and the implications of this approach in fast 3D imaging are discussed.

Monte Carlo based method for fluorescence tomographic imaging with lifetime multiplexing using time gates

PubMed Central

Chen, Jin; Venugopal, Vivek; Intes, Xavier

2011-01-01

Time-resolved fluorescence optical tomography allows 3-dimensional localization of multiple fluorophores based on lifetime contrast while providing a unique data set for improved resolution. However, to employ the full fluorescence time measurements, a light propagation model that accurately simulates weakly diffused and multiple scattered photons is required. In this article, we derive a computationally efficient Monte Carlo based method to compute time-gated fluorescence Jacobians for the simultaneous imaging of two fluorophores with lifetime contrast. The Monte Carlo based formulation is validated on a synthetic murine model simulating the uptake in the kidneys of two distinct fluorophores with lifetime contrast. Experimentally, the method is validated using capillaries filled with 2.5nmol of ICG and IRDye™800CW respectively embedded in a diffuse media mimicking the average optical properties of mice. Combining multiple time gates in one inverse problem allows the simultaneous reconstruction of multiple fluorophores with increased resolution and minimal crosstalk using the proposed formulation. PMID:21483610

Preliminary experiments on pharmacokinetic diffuse fluorescence tomography of CT-scanning mode

NASA Astrophysics Data System (ADS)

Zhang, Yanqi; Wang, Xin; Yin, Guoyan; Li, Jiao; Zhou, Zhongxing; Zhao, Huijuan; Gao, Feng; Zhang, Limin

2016-10-01

In vivo tomographic imaging of the fluorescence pharmacokinetic parameters in tissues can provide additional specific and quantitative physiological and pathological information to that of fluorescence concentration. This modality normally requires a highly-sensitive diffuse fluorescence tomography (DFT) working in dynamic way to finally extract the pharmacokinetic parameters from the measured pharmacokinetics-associated temporally-varying boundary intensity. This paper is devoted to preliminary experimental validation of our proposed direct reconstruction scheme of instantaneous sampling based pharmacokinetic-DFT: A highly-sensitive DFT system of CT-scanning mode working with parallel four photomultiplier-tube photon-counting channels is developed to generate an instantaneous sampling dataset; A direct reconstruction scheme then extracts images of the pharmacokinetic parameters using the adaptive-EKF strategy. We design a dynamic phantom that can simulate the agent metabolism in living tissue. The results of the dynamic phantom experiments verify the validity of the experiment system and reconstruction algorithms, and demonstrate that system provides good resolution, high sensitivity and quantitativeness at different pump speed.

Microscopic Optical Projection Tomography In Vivo

PubMed Central

Meyer, Heiko; Ripoll, Jorge; Tavernarakis, Nektarios

2011-01-01

We describe a versatile optical projection tomography system for rapid three-dimensional imaging of microscopic specimens in vivo. Our tomographic setup eliminates the in xy and z strongly asymmetric resolution, resulting from optical sectioning in conventional confocal microscopy. It allows for robust, high resolution fluorescence as well as absorption imaging of live transparent invertebrate animals such as C. elegans. This system offers considerable advantages over currently available methods when imaging dynamic developmental processes and animal ageing; it permits monitoring of spatio-temporal gene expression and anatomical alterations with single-cell resolution, it utilizes both fluorescence and absorption as a source of contrast, and is easily adaptable for a range of small model organisms. PMID:21559481

Computed tomographic-based quantification of emphysema and correlation to pulmonary function and mechanics.

PubMed

Washko, George R; Criner, Gerald J; Mohsenifar, Zab; Sciurba, Frank C; Sharafkhaneh, Amir; Make, Barry J; Hoffman, Eric A; Reilly, John J

2008-06-01

Computed tomographic based indices of emphysematous lung destruction may highlight differences in disease pathogenesis and further enable the classification of subjects with Chronic Obstructive Pulmonary Disease. While there are multiple techniques that can be utilized for such radiographic analysis, there is very little published information comparing the performance of these methods in a clinical case series. Our objective was to examine several quantitative and semi-quantitative methods for the assessment of the burden of emphysema apparent on computed tomographic scans and compare their ability to predict lung mechanics and function. Automated densitometric analysis was performed on 1094 computed tomographic scans collected upon enrollment into the National Emphysema Treatment Trial. Trained radiologists performed an additional visual grading of emphysema on high resolution CT scans. Full pulmonary function test results were available for correlation, with a subset of subjects having additional measurements of lung static recoil. There was a wide range of emphysematous lung destruction apparent on the CT scans and univariate correlations to measures of lung function were of modest strength. No single method of CT scan analysis clearly outperformed the rest of the group. Quantification of the burden of emphysematous lung destruction apparent on CT scan is a weak predictor of lung function and mechanics in severe COPD with no uniformly superior method found to perform this analysis. The CT based quantification of emphysema may augment pulmonary function testing in the characterization of COPD by providing complementary phenotypic information.

Clinical multiphoton and CARS microscopy

NASA Astrophysics Data System (ADS)

Breunig, H. G.; Weinigel, M.; Darvin, M. E.; Lademann, J.; König, K.

2012-03-01

We report on clinical CARS imaging of human skin in vivo with the certified hybrid multiphoton tomograph CARSDermaInspect. The CARS-DermaInspect provides simultaneous imaging of non-fluorescent intradermal lipid and water as well as imaging of two-photon excited fluorescence from intrinsic molecules. Two different excitation schemes for CARS imaging have been realized: In the first setup, a combination of fs oscillator and optical parametric oscillator provided fs-CARS pump and Stokes pulses, respectively. In the second setup a fs oscillator was combined with a photonic crystal fiber which provided a broadband spectrum. A spectral range out of the broadband-spectrum was selected and used for CARS excitation in combination with the residual fs-oscillator output. In both setups, in addition to CARS, single-beam excitation was used for imaging of two-photon excited fluorescence and second harmonic generation signals. Both CARS-excitation systems were successfully used for imaging of lipids inside the skin in vivo.

Differentiation of angiogenic burden in human cancer xenografts using a perfusion-type optical contrast agent (SIDAG)

PubMed Central

Wall, Alexander; Persigehl, Thorsten; Hauff, Peter; Licha, Kai; Schirner, Michael; Müller, Silke; von Wallbrunn, Angelika; Matuszewski, Lars; Heindel, Walter; Bremer, Christoph

2008-01-01

Introduction Use of fluorescence imaging in oncology is evolving rapidly, and nontargeted fluorochromes are currently being investigated for clinical application. Here, we investigated whether the degree of tumour angiogenesis can be assessed in vivo by planar and tomographic methods using the perfusion-type cyanine dye SIDAG (1,1'-bis- [4-sulfobutyl]indotricarbocyanine-5,5'-dicarboxylic acid diglucamide monosodium). Method Mice were xenografted with moderately (MCF7, DU4475) or highly vascularized (HT1080, MDA-MB435) tumours and scanned up to 24 hours after intravenous SIDAG injection using fluorescence reflectance imaging. Contrast-to-noise ratio was calculated for all tumours, and fluorochrome accumulation was quantified using fluorescence-mediated tomography. The vascular volume fraction of the xenografts, serving as a surrogate marker for angiogenesis, was measured using magnetic resonance imaging, and blood vessel profile (BVP) density and vascular endothelial growth factor expression were determined. Results SIDAG accumulation correlated well with angiogenic burden, with maximum contrast to noise ratio for MDA-MB435 (P < 0.0001), followed by HT1080, MCF7 and DU4475 tumours. Fluorescence-mediated tomography revealed 4.6-fold higher fluorochrome concentrations in MDA-MB435 than in DU4475 tumours (229 ± 90 nmol/l versus 49 ± 22 nmol/l; P < 0.05). The vascular volume fraction was 4.5-fold (3.58 ± 0.9% versus 0.8 ± 0.53%; P < 0.01), blood vessel profile density 5-fold (399 ± 36 BVPs/mm2 versus 78 ± 16 BVPs/mm2) and vascular endothelial growth factor expression 4-fold higher for MDA-MB435 than for DU4475 tumours. Conclusion Our data suggest that perfusion-type cyanine dyes allow assessment of angiogenesis in vivo using planar or tomographic imaging technology. They may thus facilitate characterization of solid tumours. PMID:18331624

Computed Tomographic Airway Morphology in Chronic Obstructive Pulmonary Disease. Remodeling or Innate Anatomy?

PubMed

Diaz, Alejandro A; Estépar, Raul San José; Washko, George R

2016-01-01

Computed tomographic measures of central airway morphology have been used in clinical, epidemiologic, and genetic investigation as an inference of the presence and severity of small-airway disease in smokers. Although several association studies have brought us to believe that these computed tomographic measures reflect airway remodeling, a careful review of such data and more recent evidence may reveal underappreciated complexity to these measures and limitations that prompt us to question that belief. This Perspective offers a review of seminal papers and alternative explanations of their data in the light of more recent evidence. The relationships between airway morphology and lung function are observed in subjects who never smoked, implying that native airway structure indeed contributes to lung function; computed tomographic measures of central airways such as wall area, lumen area, and total bronchial area are smaller in smokers with chronic obstructive pulmonary disease versus those without chronic obstructive pulmonary disease; and the airways are smaller as disease severity increases. The observations suggest that (1) native airway morphology likely contributes to the relationships between computed tomographic measures of airways and lung function; and (2) the presence of smaller airways in those with chronic obstructive pulmonary disease versus those without chronic obstructive pulmonary disease as well as their decrease with disease severity suggests that smokers with chronic obstructive pulmonary disease may simply have smaller airways to begin with, which put them at greater risk for the development of smoking-related disease.

Computed microtomography and X-ray fluorescence analysis for comprehensive analysis of structural changes in bone.

PubMed

Buzmakov, Alexey; Chukalina, Marina; Nikolaev, Dmitry; Schaefer, Gerald; Gulimova, Victoria; Saveliev, Sergey; Tereschenko, Elena; Seregin, Alexey; Senin, Roman; Prun, Victor; Zolotov, Denis; Asadchikov, Victor

2013-01-01

This paper presents the results of a comprehensive analysis of structural changes in the caudal vertebrae of Turner's thick-toed geckos by computer microtomography and X-ray fluorescence analysis. We present algorithms used for the reconstruction of tomographic images which allow to work with high noise level projections that represent typical conditions dictated by the nature of the samples. Reptiles, due to their ruggedness, small size, belonging to the amniote and a number of other valuable features, are an attractive model object for long-orbital experiments on unmanned spacecraft. Issues of possible changes in their bone tissue under the influence of spaceflight are the subject of discussions between biologists from different laboratories around the world.

Optimal joule heating of the subsurface

DOEpatents

Berryman, James G.; Daily, William D.

1994-01-01

A method for simultaneously heating the subsurface and imaging the effects of the heating. This method combines the use of tomographic imaging (electrical resistance tomography or ERT) to image electrical resistivity distribution underground, with joule heating by electrical currents injected in the ground. A potential distribution is established on a series of buried electrodes resulting in energy deposition underground which is a function of the resistivity and injection current density. Measurement of the voltages and currents also permits a tomographic reconstruction of the resistivity distribution. Using this tomographic information, the current injection pattern on the driving electrodes can be adjusted to change the current density distribution and thus optimize the heating. As the heating changes conditions, the applied current pattern can be repeatedly adjusted (based on updated resistivity tomographs) to affect real time control of the heating.

Fluorescence lifetime imaging of induced pluripotent stem cells

NASA Astrophysics Data System (ADS)

Uchugonova, Aisada; Batista, Ana; König, Karsten

2014-02-01

The multiphoton FLIM tomograph MPTflex with its flexible scan head, articulated arm, and the tunable femtosecond laser source was employed to study cell monolayers and 3D cell clusters. FLIM was performed with 250 ps temporal resolution and submicron special resolution using time-correlated single photon counting. The autofluorescence based on NAD(P)H and flavins/flavoproteins has been measured in mouse embryonic fibroblasts, induced pluripotent stem cells (iPS cells) originated from mouse embryonic fibroblasts and non-proliferative mouse embryonic fibroblasts.

Optimal joule heating of the subsurface

DOEpatents

Berryman, J.G.; Daily, W.D.

1994-07-05

A method for simultaneously heating the subsurface and imaging the effects of the heating is disclosed. This method combines the use of tomographic imaging (electrical resistance tomography or ERT) to image electrical resistivity distribution underground, with joule heating by electrical currents injected in the ground. A potential distribution is established on a series of buried electrodes resulting in energy deposition underground which is a function of the resistivity and injection current density. Measurement of the voltages and currents also permits a tomographic reconstruction of the resistivity distribution. Using this tomographic information, the current injection pattern on the driving electrodes can be adjusted to change the current density distribution and thus optimize the heating. As the heating changes conditions, the applied current pattern can be repeatedly adjusted (based on updated resistivity tomographs) to affect real time control of the heating.

Combined synchrotron X-ray tomography and X-ray powder diffraction using a fluorescing metal foil.

PubMed

Kappen, P; Arhatari, B D; Luu, M B; Balaur, E; Caradoc-Davies, T

2013-06-01

This study realizes the concept of simultaneous micro-X-ray computed tomography and X-ray powder diffraction using a synchrotron beamline. A thin zinc metal foil was placed in the primary, monochromatic synchrotron beam to generate a divergent wave to propagate through the samples of interest onto a CCD detector for tomographic imaging, thus removing the need for large beam illumination and high spatial resolution detection. Both low density materials (kapton tubing and a piece of plant) and higher density materials (Egyptian faience) were investigated, and elemental contrast was explored for the example of Cu and Ni meshes. The viability of parallel powder diffraction using the direct beam transmitted through the foil was demonstrated. The outcomes of this study enable further development of the technique towards in situ tomography∕diffraction studies combining micrometer and crystallographic length scales, and towards elemental contrast imaging and reconstruction methods using well defined fluorescence outputs from combinations of known fluorescence targets (elements).

MicroXRF tomographic visualization of zinc and iron in the zebrafish embryo at the onset of the hatching period

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bourassa, Daisy; Gleber, Sophie-Charlotte; Vogt, Stefan

2016-01-01

Transition metals such as zinc, copper, and iron play key roles in cellular proliferation, cell differentiation, growth, and development. Over the past decade, advances in synchrotron X-ray fluorescence instrumentation presented new opportunities for the three-dimensional mapping of trace metal distributions within intact specimens. Taking advantage of microXRF tomography, we visualized the 3D distribution of zinc and iron in a zebrafish embryo at the onset of the hatching period. The reconstructed volumetric data revealed distinct differences in the elemental distributions, with zinc predominantly localized to the yolk and yolk extension, and iron to various regions of the brain as well asmore » the myotome extending along the dorsal side of the embryo. The data set complements an earlier tomographic study of an embryo at the pharyngula stage (24 hpf), thus offering new insights into the trace metal distribution at key stages of embryonic development.« less

Tomographic imaging using poissonian detector data

DOEpatents

Aspelmeier, Timo; Ebel, Gernot; Hoeschen, Christoph

2013-10-15

An image reconstruction method for reconstructing a tomographic image (f.sub.j) of a region of investigation within an object (1), comprises the steps of providing detector data (y.sub.i) comprising Poisson random values measured at an i-th of a plurality of different positions, e.g. i=(k,l) with pixel index k on a detector device and angular index l referring to both the angular position (.alpha..sub.l) and the rotation radius (r.sub.l) of the detector device (10) relative to the object (1), providing a predetermined system matrix A.sub.ij assigning a j-th voxel of the object (1) to the i-th detector data (y.sub.i), and reconstructing the tomographic image (f.sub.j) based on the detector data (y.sub.i), said reconstructing step including a procedure of minimizing a functional F(f) depending on the detector data (y.sub.i) and the system matrix A.sub.ij and additionally including a sparse or compressive representation of the object (1) in an orthobasis T, wherein the tomographic image (f.sub.j) represents the global minimum of the functional F(f). Furthermore, an imaging method and an imaging device using the image reconstruction method are described.

Identifying microbial habitats in soil using quantum dots and x-ray fluorescence microtomography

NASA Astrophysics Data System (ADS)

O'Brien, S. L.; Whiteside, M. D.; Sholto-Douglas, D.; Dohnalkova, A.; Durall, D. M.; Gursoy, D.; Jones, M. D.; Kovarik, L.; Lai, B.; Roehrig, C.; Sullivan, S.; Vogt, S.; Kemner, K. M.

2015-12-01

The metabolic activities of soil microbes are the primary drivers of biogeochemical processes controlling the terrestrial carbon cycle, nutrient availability to plants, contaminant remediation, water quality, and other ecosystem services. However, we have a limited understanding of microbial metabolic processes such as nutrient uptake rates, substrate preferences, or how microbes and microbial metabolism are distributed throughout the three-dimensional pore network of the soil. Here we use a novel combination of imaging techniques with quantum dots (QDs, engineered semiconductor nanoparticles that produce size or composition-dependent fluorescence) to locate bacteria in the three-dimensional pore network of a soil aggregate. First, we show using confocal and aberration-corrected transmission electron microscopies that bacteria (Bacillus subtilis, Pseudomonas fluorescens, and Pseudomonas protogens) actively take up and internalize CdSe/ZnS core/shell QDs conjugated to biologically relevant substrates. Next, we show that cells bearing QDs can be identified using fluorescence imaging with hard x-rays at 2ID-D at the Advanced Photon Source (APS). Finally, we demonstrate that the Se constituent to the QDs can be used to label bacteria in three-dimensional tomographic reconstructions of natural soil at 0.5 nm spatial resolution using hard x-rays at 2ID-E at the APS. This is the first time soil bacteria have been imaged in the intact soil matrix at such high resolution. These results offer a new way to experimentally investigate basic bacterial ecology in situ, revealing constraints on microbial function in soil that will help improve connections between pore-scale and ecosystem-scale processes in models.

Localization of pulmonary nodules using navigation bronchoscope and a near-infrared fluorescence thoracoscope.

PubMed

Anayama, Takashi; Qiu, Jimmy; Chan, Harley; Nakajima, Takahiro; Weersink, Robert; Daly, Michael; McConnell, Judy; Waddell, Thomas; Keshavjee, Shaf; Jaffray, David; Irish, Jonathan C; Hirohashi, Kentaro; Wada, Hironobu; Orihashi, Kazumasa; Yasufuku, Kazuhiro

2015-01-01

Video-assisted thoracoscopic wedge resection of multiple small, non-visible, and nonpalpable pulmonary nodules is a clinical challenge. We propose an ultra-minimally invasive technique for localization of pulmonary nodules using the electromagnetic navigation bronchoscope (ENB)-guided transbronchial indocyanine green (ICG) injection and intraoperative fluorescence detection with a near-infrared (NIR) fluorescence thoracoscope. Fluorescence properties of ICG topically injected into the lung parenchyma were determined using a resected porcine lung. The combination of ENB-guided ICG injection and NIR fluorescence detection was tested using a live porcine model. An electromagnetic sensor integrated flexible bronchoscope was geometrically registered to the three-dimensional chest computed tomographic image data by way of a real-time electromagnetic tracking system. The ICG mixed with iopamidol was injected into the pulmonary nodules by ENB guidance; ICG fluorescence was visualized by a near-infrared (NIR) thoracoscope. The ICG existing under 24-mm depth of inflated lung was detectable by the NIR fluorescence thoracoscope. The size of the fluorescence spot made by 0.1 mL of ICG was 10.4 ± 2.2 mm. An ICG or iopamidol spot remained at the injected point of the lung for more than 6 hours in vivo. The ICG fluorescence spot injected into the pulmonary nodule with ENB guidance was identified at the pulmonary nodule with the NIR thoracoscope. The ENB-guided transbronchial ICG injection and intraoperative NIR thoracoscopic detection is a feasible method to localize multiple pulmonary nodules. Copyright © 2015 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Image processing pipeline for synchrotron-radiation-based tomographic microscopy.

PubMed

Hintermüller, C; Marone, F; Isenegger, A; Stampanoni, M

2010-07-01

With synchrotron-radiation-based tomographic microscopy, three-dimensional structures down to the micrometer level can be visualized. Tomographic data sets typically consist of 1000 to 1500 projections of 1024 x 1024 to 2048 x 2048 pixels and are acquired in 5-15 min. A processing pipeline has been developed to handle this large amount of data efficiently and to reconstruct the tomographic volume within a few minutes after the end of a scan. Just a few seconds after the raw data have been acquired, a selection of reconstructed slices is accessible through a web interface for preview and to fine tune the reconstruction parameters. The same interface allows initiation and control of the reconstruction process on the computer cluster. By integrating all programs and tools, required for tomographic reconstruction into the pipeline, the necessary user interaction is reduced to a minimum. The modularity of the pipeline allows functionality for new scan protocols to be added, such as an extended field of view, or new physical signals such as phase-contrast or dark-field imaging etc.

Optimal parameters for near infrared fluorescence imaging of amyloid plaques in Alzheimer’s disease mouse models

PubMed Central

Raymond, S B; Kumar, A T N; Boas, D A; Bacskai, B J

2012-01-01

Amyloid-β plaques are an Alzheimer’s disease biomarker which present unique challenges for near-infrared fluorescence tomography because of size (<50 μm diameter) and distribution. We used high-resolution simulations of fluorescence in a digital Alzheimer’s disease mouse model to investigate the optimal fluorophore and imaging parameters for near-infrared fluorescence tomography of amyloid plaques. Fluorescence was simulated for amyloid-targeted probes with emission at 630 and 800 nm, plaque-to-background ratios from 1–1000, amyloid burden from 0–10%, and for transmission and reflection measurement geometries. Fluorophores with high plaque-to-background contrast ratios and 800 nm emission performed significantly better than current amyloid imaging probes. We tested idealized fluorophores in transmission and full-angle tomographic measurement schemes (900 source–detector pairs), with and without anatomical priors. Transmission reconstructions demonstrated strong linear correlation with increasing amyloid burden, but underestimated fluorescence yield and suffered from localization artifacts. Full-angle measurements did not improve upon the transmission reconstruction qualitatively or in semi-quantitative measures of accuracy; anatomical and initial-value priors did improve reconstruction localization and accuracy for both transmission and full-angle schemes. Region-based reconstructions, in which the unknowns were reduced to a few distinct anatomical regions, produced highly accurate yield estimates for cortex, hippocampus and brain regions, even with a reduced number of measurements (144 source–detector pairs). PMID:19794239

Time reversal optical tomography locates fluorescent targets in a turbid medium

NASA Astrophysics Data System (ADS)

Wu, Binlin; Cai, W.; Gayen, S. K.

2013-03-01

A fluorescence optical tomography approach that extends time reversal optical tomography (TROT) to locate fluorescent targets embedded in a turbid medium is introduced. It uses a multi-source illumination and multi-detector signal acquisition scheme, along with TR matrix formalism, and multiple signal classification (MUSIC) to construct pseudo-image of the targets. The samples consisted of a single or two small tubes filled with water solution of Indocyanine Green (ICG) dye as targets embedded in a 250 mm × 250 mm × 60 mm rectangular cell filled with Intralipid-20% suspension as the scattering medium. The ICG concentration was 1μM, and the Intralipid-20% concentration was adjusted to provide ~ 1-mm transport length for both excitation wavelength of 790 nm and fluorescence wavelength around 825 nm. The data matrix was constructed using the diffusely transmitted fluorescence signals for all scan positions, and the TR matrix was constructed by multiplying data matrix with its transpose. A pseudo spectrum was calculated using the signal subspace of the TR matrix. Tomographic images were generated using the pseudo spectrum. The peaks in the pseudo images provided locations of the target(s) with sub-millimeter accuracy. Concurrent transmission TROT measurements corroborated fluorescence-TROT findings. The results demonstrate that TROT is a fast approach that can be used to obtain accurate three-dimensional position information of fluorescence targets embedded deep inside a highly scattering medium, such as, a contrast-enhanced tumor in a human breast.

Multi-scale volumetric cell and tissue imaging based on optical projection tomography (Conference Presentation)

NASA Astrophysics Data System (ADS)

Ban, Sungbea; Cho, Nam Hyun; Ryu, Yongjae; Jung, Sunwoo; Vavilin, Andrey; Min, Eunjung; Jung, Woonggyu

2016-04-01

Optical projection tomography is a new optical imaging method for visualizing small biological specimens in three dimension. The most important advantage of OPT is to fill the gap between MRI and confocal microscope for the specimen having the range of 1-10 mm. Thus, it has been mainly used for whole-mount small animals and developmental study since this imaging modality was developed. The ability of OPT delivering anatomical and functional information of relatively large tissue in 3D has made it a promising platform in biomedical research. Recently, the potential of OPT spans its coverage to cellular scale. Even though there are increasing demand to obtain better understanding of cellular dynamics, only few studies to visualize cellular structure, shape, size and functional morphology over tissue has been investigated in existing OPT system due to its limited field of view. In this study, we develop a novel optical imaging system for 3D cellular imaging with OPT integrated with dynamic focusing technique. Our tomographic setup has great potential to be used for identifying cell characteristic in tissue because it can provide selective contrast on dynamic focal plane allowing for fluorescence as well as absorption. While the dominant contrast of optical imaging technique is to use the fluorescence for detecting certain target only, the newly developed OPT system will offer considerable advantages over currently available method when imaging cellar molecular dynamics by permitting contrast variation. By achieving multi-contrast, it is expected for this new imaging system to play an important role in delivering better cytological information to pathologist.

Automatic transfer function generation for volume rendering of high-resolution x-ray 3D digital mammography images

NASA Astrophysics Data System (ADS)

Alyassin, Abdal M.

2002-05-01

3D Digital mammography (3DDM) is a new technology that provides high resolution X-ray breast tomographic data. Like any other tomographic medical imaging modalities, viewing a stack of tomographic images may require time especially if the images are of large matrix size. In addition, it may cause difficulty to conceptually construct 3D breast structures. Therefore, there is a need to readily visualize the data in 3D. However, one of the issues that hinder the usage of volume rendering (VR) is finding an automatic way to generate transfer functions that efficiently map the important diagnostic information in the data. We have developed a method that randomly samples the volume. Based on the mean and the standard deviation of these samples, the technique determines the lower limit and upper limit of a piecewise linear ramp transfer function. We have volume rendered several 3DDM data using this technique and compared visually the outcome with the result from a conventional automatic technique. The transfer function generated through the proposed technique provided superior VR images over the conventional technique. Furthermore, the improvement in the reproducibility of the transfer function correlated with the number of samples taken from the volume at the expense of the processing time.

Energy response calibration of photon-counting detectors using x-ray fluorescence: a feasibility study.

PubMed

Cho, H-M; Ding, H; Ziemer, B P; Molloi, S

2014-12-07

Accurate energy calibration is critical for the application of energy-resolved photon-counting detectors in spectral imaging. The aim of this study is to investigate the feasibility of energy response calibration and characterization of a photon-counting detector using x-ray fluorescence. A comprehensive Monte Carlo simulation study was performed using Geant4 Application for Tomographic Emission (GATE) to investigate the optimal technique for x-ray fluorescence calibration. Simulations were conducted using a 100 kVp tungsten-anode spectra with 2.7 mm Al filter for a single pixel cadmium telluride (CdTe) detector with 3 × 3 mm(2) in detection area. The angular dependence of x-ray fluorescence and scatter background was investigated by varying the detection angle from 20° to 170° with respect to the beam direction. The effects of the detector material, shape, and size on the recorded x-ray fluorescence were investigated. The fluorescent material size effect was considered with and without the container for the fluorescent material. In order to provide validation for the simulation result, the angular dependence of x-ray fluorescence from five fluorescent materials was experimentally measured using a spectrometer. Finally, eleven of the fluorescent materials were used for energy calibration of a CZT-based photon-counting detector. The optimal detection angle was determined to be approximately at 120° with respect to the beam direction, which showed the highest fluorescence to scatter ratio (FSR) with a weak dependence on the fluorescent material size. The feasibility of x-ray fluorescence for energy calibration of photon-counting detectors in the diagnostic x-ray energy range was verified by successfully calibrating the energy response of a CZT-based photon-counting detector. The results of this study can be used as a guideline to implement the x-ray fluorescence calibration method for photon-counting detectors in a typical imaging laboratory.

Energy response calibration of photon-counting detectors using x-ray fluorescence: a feasibility study

NASA Astrophysics Data System (ADS)

Cho, H.-M.; Ding, H.; Ziemer, BP; Molloi, S.

2014-12-01

Accurate energy calibration is critical for the application of energy-resolved photon-counting detectors in spectral imaging. The aim of this study is to investigate the feasibility of energy response calibration and characterization of a photon-counting detector using x-ray fluorescence. A comprehensive Monte Carlo simulation study was performed using Geant4 Application for Tomographic Emission (GATE) to investigate the optimal technique for x-ray fluorescence calibration. Simulations were conducted using a 100 kVp tungsten-anode spectra with 2.7 mm Al filter for a single pixel cadmium telluride (CdTe) detector with 3  ×  3 mm2 in detection area. The angular dependence of x-ray fluorescence and scatter background was investigated by varying the detection angle from 20° to 170° with respect to the beam direction. The effects of the detector material, shape, and size on the recorded x-ray fluorescence were investigated. The fluorescent material size effect was considered with and without the container for the fluorescent material. In order to provide validation for the simulation result, the angular dependence of x-ray fluorescence from five fluorescent materials was experimentally measured using a spectrometer. Finally, eleven of the fluorescent materials were used for energy calibration of a CZT-based photon-counting detector. The optimal detection angle was determined to be approximately at 120° with respect to the beam direction, which showed the highest fluorescence to scatter ratio (FSR) with a weak dependence on the fluorescent material size. The feasibility of x-ray fluorescence for energy calibration of photon-counting detectors in the diagnostic x-ray energy range was verified by successfully calibrating the energy response of a CZT-based photon-counting detector. The results of this study can be used as a guideline to implement the x-ray fluorescence calibration method for photon-counting detectors in a typical imaging laboratory.

Energy response calibration of photon-counting detectors using X-ray fluorescence: a feasibility study

PubMed Central

Cho, H-M; Ding, H; Ziemer, BP; Molloi, S

2014-01-01

Accurate energy calibration is critical for the application of energy-resolved photon-counting detectors in spectral imaging. The aim of this study is to investigate the feasibility of energy response calibration and characterization of a photon-counting detector using X-ray fluorescence. A comprehensive Monte Carlo simulation study was performed using Geant4 Application for Tomographic Emission (GATE) to investigate the optimal technique for X-ray fluorescence calibration. Simulations were conducted using a 100 kVp tungsten-anode spectra with 2.7 mm Al filter for a single pixel cadmium telluride (CdTe) detector with 3 × 3 mm2 in detection area. The angular dependence of X-ray fluorescence and scatter background was investigated by varying the detection angle from 20° to 170° with respect to the beam direction. The effects of the detector material, shape, and size on the recorded X-ray fluorescence were investigated. The fluorescent material size effect was considered with and without the container for the fluorescent material. In order to provide validation for the simulation result, the angular dependence of X-ray fluorescence from five fluorescent materials was experimentally measured using a spectrometer. Finally, eleven of the fluorescent materials were used for energy calibration of a CZT-based photon-counting detector. The optimal detection angle was determined to be approximately at 120° with respect to the beam direction, which showed the highest fluorescence to scatter ratio (FSR) with a weak dependence on the fluorescent material size. The feasibility of X-ray fluorescence for energy calibration of photon-counting detectors in the diagnostic X-ray energy range was verified by successfully calibrating the energy response of a CZT-based photon-counting detector. The results of this study can be used as a guideline to implement the X-ray fluorescence calibration method for photon-counting detectors in a typical imaging laboratory. PMID:25369288

3D multimodal cardiac data reconstruction using angiography and computerized tomographic angiography registration.

PubMed

Moosavi Tayebi, Rohollah; Wirza, Rahmita; Sulaiman, Puteri S B; Dimon, Mohd Zamrin; Khalid, Fatimah; Al-Surmi, Aqeel; Mazaheri, Samaneh

2015-04-22

Computerized tomographic angiography (3D data representing the coronary arteries) and X-ray angiography (2D X-ray image sequences providing information about coronary arteries and their stenosis) are standard and popular assessment tools utilized for medical diagnosis of coronary artery diseases. At present, the results of both modalities are individually analyzed by specialists and it is difficult for them to mentally connect the details of these two techniques. The aim of this work is to assist medical diagnosis by providing specialists with the relationship between computerized tomographic angiography and X-ray angiography. In this study, coronary arteries from two modalities are registered in order to create a 3D reconstruction of the stenosis position. The proposed method starts with coronary artery segmentation and labeling for both modalities. Then, stenosis and relevant labeled artery in X-ray angiography image are marked by a specialist. Proper control points for the marked artery in both modalities are automatically detected and normalized. Then, a geometrical transformation function is computed using these control points. Finally, this function is utilized to register the marked artery from the X-ray angiography image on the computerized tomographic angiography and get the 3D position of the stenosis lesion. The result is a 3D informative model consisting of stenosis and coronary arteries' information from the X-ray angiography and computerized tomographic angiography modalities. The results of the proposed method for coronary artery segmentation, labeling and 3D reconstruction are evaluated and validated on the dataset containing both modalities. The advantage of this method is to aid specialists to determine a visual relationship between the correspondent coronary arteries from two modalities and also set up a connection between stenosis points from an X-ray angiography along with their 3D positions on the coronary arteries from computerized tomographic angiography. Moreover, another benefit of this work is that the medical acquisition standards remain unchanged, which means that no calibration in the acquisition devices is required. It can be applied on most computerized tomographic angiography and angiography devices.

Entropy-Bayesian Inversion of Time-Lapse Tomographic GPR data for Monitoring Dielectric Permittivity and Soil Moisture Variations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hou, Z; Terry, N; Hubbard, S S

2013-02-12

In this study, we evaluate the possibility of monitoring soil moisture variation using tomographic ground penetrating radar travel time data through Bayesian inversion, which is integrated with entropy memory function and pilot point concepts, as well as efficient sampling approaches. It is critical to accurately estimate soil moisture content and variations in vadose zone studies. Many studies have illustrated the promise and value of GPR tomographic data for estimating soil moisture and associated changes, however, challenges still exist in the inversion of GPR tomographic data in a manner that quantifies input and predictive uncertainty, incorporates multiple data types, handles non-uniquenessmore » and nonlinearity, and honors time-lapse tomograms collected in a series. To address these challenges, we develop a minimum relative entropy (MRE)-Bayesian based inverse modeling framework that non-subjectively defines prior probabilities, incorporates information from multiple sources, and quantifies uncertainty. The framework enables us to estimate dielectric permittivity at pilot point locations distributed within the tomogram, as well as the spatial correlation range. In the inversion framework, MRE is first used to derive prior probability distribution functions (pdfs) of dielectric permittivity based on prior information obtained from a straight-ray GPR inversion. The probability distributions are then sampled using a Quasi-Monte Carlo (QMC) approach, and the sample sets provide inputs to a sequential Gaussian simulation (SGSim) algorithm that constructs a highly resolved permittivity/velocity field for evaluation with a curved-ray GPR forward model. The likelihood functions are computed as a function of misfits, and posterior pdfs are constructed using a Gaussian kernel. Inversion of subsequent time-lapse datasets combines the Bayesian estimates from the previous inversion (as a memory function) with new data. The memory function and pilot point design takes advantage of the spatial-temporal correlation of the state variables. We first apply the inversion framework to a static synthetic example and then to a time-lapse GPR tomographic dataset collected during a dynamic experiment conducted at the Hanford Site in Richland, WA. We demonstrate that the MRE-Bayesian inversion enables us to merge various data types, quantify uncertainty, evaluate nonlinear models, and produce more detailed and better resolved estimates than straight-ray based inversion; therefore, it has the potential to improve estimates of inter-wellbore dielectric permittivity and soil moisture content and to monitor their temporal dynamics more accurately.« less

Entropy-Bayesian Inversion of Time-Lapse Tomographic GPR data for Monitoring Dielectric Permittivity and Soil Moisture Variations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hou, Zhangshuan; Terry, Neil C.; Hubbard, Susan S.

2013-02-22

In this study, we evaluate the possibility of monitoring soil moisture variation using tomographic ground penetrating radar travel time data through Bayesian inversion, which is integrated with entropy memory function and pilot point concepts, as well as efficient sampling approaches. It is critical to accurately estimate soil moisture content and variations in vadose zone studies. Many studies have illustrated the promise and value of GPR tomographic data for estimating soil moisture and associated changes, however, challenges still exist in the inversion of GPR tomographic data in a manner that quantifies input and predictive uncertainty, incorporates multiple data types, handles non-uniquenessmore » and nonlinearity, and honors time-lapse tomograms collected in a series. To address these challenges, we develop a minimum relative entropy (MRE)-Bayesian based inverse modeling framework that non-subjectively defines prior probabilities, incorporates information from multiple sources, and quantifies uncertainty. The framework enables us to estimate dielectric permittivity at pilot point locations distributed within the tomogram, as well as the spatial correlation range. In the inversion framework, MRE is first used to derive prior probability density functions (pdfs) of dielectric permittivity based on prior information obtained from a straight-ray GPR inversion. The probability distributions are then sampled using a Quasi-Monte Carlo (QMC) approach, and the sample sets provide inputs to a sequential Gaussian simulation (SGSIM) algorithm that constructs a highly resolved permittivity/velocity field for evaluation with a curved-ray GPR forward model. The likelihood functions are computed as a function of misfits, and posterior pdfs are constructed using a Gaussian kernel. Inversion of subsequent time-lapse datasets combines the Bayesian estimates from the previous inversion (as a memory function) with new data. The memory function and pilot point design takes advantage of the spatial-temporal correlation of the state variables. We first apply the inversion framework to a static synthetic example and then to a time-lapse GPR tomographic dataset collected during a dynamic experiment conducted at the Hanford Site in Richland, WA. We demonstrate that the MRE-Bayesian inversion enables us to merge various data types, quantify uncertainty, evaluate nonlinear models, and produce more detailed and better resolved estimates than straight-ray based inversion; therefore, it has the potential to improve estimates of inter-wellbore dielectric permittivity and soil moisture content and to monitor their temporal dynamics more accurately.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cho, H; Ding, H; Ziemer, B

Purpose: To investigate the feasibility of energy calibration and energy response characterization of a photon counting detector using x-ray fluorescence. Methods: A comprehensive Monte Carlo simulation study was done to investigate the influence of various geometric components on the x-ray fluorescence measurement. Different materials, sizes, and detection angles were simulated using Geant4 Application for Tomographic Emission (GATE) Monte Carlo package. Simulations were conducted using 100 kVp tungsten-anode spectra with 2 mm Al filter for a single pixel cadmium telluride (CdTe) detector with 3 × 3 mm2 in detection area. The fluorescence material was placed 300 mm away from both themore » x-ray source and the detector. For angular dependence measurement, the distance was decreased to 30 mm to reduce the simulation time. Compound materials, containing silver, barium, gadolinium, hafnium, and gold in cylindrical shape, were simulated. The object size varied from 5 to 100 mm in diameter. The angular dependence of fluorescence and scatter were simulated from 20° to 170° with an incremental step of 10° to optimize the fluorescence to scatter ratio. Furthermore, the angular dependence was also experimentally measured using a spectrometer (X-123CdTe, Amptek Inc., MA) to validate the simulation results. Results: The detection angle between 120° to 160° resulted in more optimal x-ray fluorescence to scatter ratio. At a detection angle of 120°, the object size did not have a significant effect on the fluorescence to scatter ratio. The experimental results of fluorescence angular dependence are in good agreement with the simulation results. The Kα and Kβ peaks of five materials could be identified. Conclusion: The simulation results show that the x-ray fluorescence procedure has the potential to be used for detector energy calibration and detector response characteristics by using the optimal system geometry.« less

A novel optical detector concept for dedicated and multi-modality in vivo small animal imaging

NASA Astrophysics Data System (ADS)

Peter, Jörg; Schulz, Ralf B.; Unholtz, Daniel; Semmler, Wolfhard

2007-07-01

An optical detector suitable for inclusion in tomographic arrangements for non-contact in vivo bioluminescence and fluorescence imaging applications is proposed. It consists of a microlens array (MLA) intended for field-of-view definition, a large-field complementary metal-oxide-semiconductor (CMOS) chip for light detection, a septum mask for cross-talk suppression, and an exchangeable filter to block excitation light. Prototype detector units with sensitive areas of 2.5 cm x 5 cm each were assembled. The CMOS sensor constitutes a 512 x 1024 photodiode matrix at 48 μm pixel pitch. Refractive MLAs with plano-convex lenses of 480 μm in diameter and pitch were selected resulting in a 55 x 105 lens matrix. The CMOS sensor is aligned on the focal plane of the MLA at 2.15mm distance. To separate individual microlens images an opaque multi-bore septum mask of 2.1mm in thickness and bore diameters of 400 μm at 480 μm pitch, aligned with the lens pattern, is placed between MLA and CMOS. Intrinsic spatial detector resolution and sensitivity was evaluated experimentally as a function of detector-object distance. Due to its small overall dimensions such detectors can be favorably packed for tomographic imaging (optical diffusion tomography, ODT) yielding complete 2 π field-of-view coverage. We also present a design study of a device intended to simultaneously image positron labeled substrates (positron emission tomography, PET) and optical molecular probes in small animals such as mice and rats. It consists of a cylindrical allocation of optical detector units which form an inner detector ring while PET detector blocks are mounted in radial extension, those gaining complementary information in a single, intrinsically coregistered experimental data acquisition study. Finally, in a second design study we propose a method for integrated optical and magnetic resonance imaging (MRI) which yields in vivo functional/molecular information that is intrinsically registered with the anatomy of the image object.

Three-dimensional refractive index and fluorescence tomography using structured illumination (Conference Presentation)

NASA Astrophysics Data System (ADS)

Park, GwangSik; Shin, SeungWoo; Kim, Kyoohyun; Park, YongKeun

2017-02-01

Optical diffraction tomography (ODT) has been an emerging optical technique for label-free imaging of three-dimensional (3-D) refractive index (RI) distribution of biological samples. ODT employs interferometric microscopy for measuring multiple holograms of samples with various incident angles, from which the Fourier diffraction theorem reconstructs the 3-D RI distribution of samples from retrieved complex optical fields. Since the RI value is linearly proportional to the protein concentration of biological samples where the proportional coefficient is called as refractive index increment (RII), reconstructed 3-D RI tomograms provide precise structural and biochemical information of individual biological samples. Because most proteins have similar RII value, however, ODT has limited molecular specificity, especially for imaging eukaryotic cells having various types of proteins and subcellular organelles. Here, we present an ODT system combined with structured illumination microscopy which can measure the 3-D RI distribution of biological samples as well as 3-D super-resolution fluorescent images in the same optical setup. A digital micromirror device (DMD) controls the incident angle of the illumination beam for tomogram reconstruction, and the same DMD modulates the structured illumination pattern of the excitation beam for super-resolution fluorescent imaging. We first validate the proposed method for simultaneous optical diffraction tomographic imaging and super-resolution fluorescent imaging of fluorescent beads. The proposed method is also exploited for various biological samples.

Quantitative tomographic imaging of intermolecular FRET in small animals

PubMed Central

Venugopal, Vivek; Chen, Jin; Barroso, Margarida; Intes, Xavier

2012-01-01

Forster resonance energy transfer (FRET) is a nonradiative transfer of energy between two fluorescent molecules (a donor and an acceptor) in nanometer range proximity. FRET imaging methods have been applied to proteomic studies and drug discovery applications based on intermolecular FRET efficiency measurements and stoichiometric measurements of FRET interaction as quantitative parameters of interest. Importantly, FRET provides information about biomolecular interactions at a molecular level, well beyond the diffraction limits of standard microscopy techniques. The application of FRET to small animal imaging will allow biomedical researchers to investigate physiological processes occurring at nanometer range in vivo as well as in situ. In this work a new method for the quantitative reconstruction of FRET measurements in small animals, incorporating a full-field tomographic acquisition system with a Monte Carlo based hierarchical reconstruction scheme, is described and validated in murine models. Our main objective is to estimate the relative concentration of two forms of donor species, i.e., a donor molecule involved in FRETing to an acceptor close by and a nonFRETing donor molecule. PMID:23243567

Spatial frequency domain tomography of protoporphyrin IX fluorescence in preclinical glioma models

PubMed Central

Konecky, Soren D.; Owen, Chris M.; Rice, Tyler; Valdés, Pablo A.; Kolste, Kolbein; Wilson, Brian C.; Leblond, Frederic; Roberts, David W.; Paulsen, Keith D.

2012-01-01

Abstract. Multifrequency (0 to 0.3  mm−1), multiwavelength (633, 680, 720, 800, and 820 nm) spatial frequency domain imaging (SFDI) of 5-aminolevulinic acid-induced protoporphyrin IX (PpIX) was used to recover absorption, scattering, and fluorescence properties of glioblastoma multiforme spheroids in tissue-simulating phantoms and in vivo in a mouse model. Three-dimensional tomographic reconstructions of the frequency-dependent remitted light localized the depths of the spheroids within 500 μm, and the total amount of PpIX in the reconstructed images was constant to within 30% when spheroid depth was varied. In vivo tumor-to-normal contrast was greater than ∼1.5 in reduced scattering coefficient for all wavelengths and was ∼1.3 for the tissue concentration of deoxyhemoglobin (ctHb). The study demonstrates the feasibility of SFDI for providing enhanced image guidance during surgical resection of brain tumors. PMID:22612131

Hyperspectral image reconstruction for x-ray fluorescence tomography

DOE PAGES

Gürsoy, Doǧa; Biçer, Tekin; Lanzirotti, Antonio; ...

2015-01-01

A penalized maximum-likelihood estimation is proposed to perform hyperspectral (spatio-spectral) image reconstruction for X-ray fluorescence tomography. The approach minimizes a Poisson-based negative log-likelihood of the observed photon counts, and uses a penalty term that has the effect of encouraging local continuity of model parameter estimates in both spatial and spectral dimensions simultaneously. The performance of the reconstruction method is demonstrated with experimental data acquired from a seed of arabidopsis thaliana collected at the 13-ID-E microprobe beamline at the Advanced Photon Source. The resulting element distribution estimates with the proposed approach show significantly better reconstruction quality than the conventional analytical inversionmore » approaches, and allows for a high data compression factor which can reduce data acquisition times remarkably. In particular, this technique provides the capability to tomographically reconstruct full energy dispersive spectra without compromising reconstruction artifacts that impact the interpretation of results.« less

Studies of the Processing of Single Words Using Positron Tomographic Measures of Cerebral Blood Flow Change.

DTIC Science & Technology

1987-01-01

BLOOD FLOW CHANGE Steven E. Petersen, Peter T. Fox, Michael I. Posner, Marcus Raichle McDonnell Center for Studies of Higher Brain Function...Single Words Using Positron Emission Tomographic Measurements of Cerebral Blood Flow Change *= ’I PERSONAL AUTHOR(S) * Petersen, Steven E. 13a. TYPE OF...CHANGE Steven E. Petersen, Peter T. Fox, Michael I. Posner, Marcus E. Raichle INTRODUCTION Language is an essential characteristic of the human

Imaging and characterizing cells using tomography

PubMed Central

Do, Myan; Isaacson, Samuel A.; McDermott, Gerry; Le Gros, Mark A.; Larabell, Carolyn A.

2015-01-01

We can learn much about cell function by imaging and quantifying sub-cellular structures, especially if this is done non-destructively without altering said structures. Soft x-ray tomography (SXT) is a high-resolution imaging technique for visualizing cells and their interior structure in 3D. A tomogram of the cell, reconstructed from a series of 2D projection images, can be easily segmented and analyzed. SXT has a very high specimen throughput compared to other high-resolution structure imaging modalities; for example, tomographic data for reconstructing an entire eukaryotic cell is acquired in a matter of minutes. SXT visualizes cells without the need for chemical fixation, dehydration, or staining of the specimen. As a result, the SXT reconstructions are close representations of cells in their native state. SXT is applicable to most cell types. The deep penetration of soft x-rays allows cells, even mammalian cells, to be imaged without being sectioned. Image contrast in SXT is generated by the differential attenuation soft x-ray illumination as it passes through the specimen. Accordingly, each voxel in the tomographic reconstruction has a measured linear absorption coefficient (LAC) value. LAC values are quantitative and give rise to each sub-cellular component having a characteristic LAC profile, allowing organelles to be identified and segmented from the milieu of other cell contents. In this chapter, we describe the fundamentals of SXT imaging and how this technique can answer real world questions in the study of the nucleus. We also describe the development of correlative methods for the localization of specific molecules in a SXT reconstruction. The combination of fluorescence and SXT data acquired from the same specimen produces composite 3D images, rich with detailed information on the inner workings of cells. PMID:25602704

Large Scale Solution Assembly of Quantum Dot - Gold Nanorod Architectures with Plasmon Enhanced Fluorescence (Postprint)

DTIC Science & Technology

2013-09-01

around the AuNR. This is illustrated in Figure 3, which compi!res brightfield,scanningTEM ( STEM ), and 3D tomographic reconstruction of QD,/AuNR. The...distribution unlimited ... Cll u 1𔃺 Q. II) QDn/AuNR 1-5 6-10 11-15 16-20 >20 ~ 60 c ~ "’ 40 ..Q ·~ u; c 20 k 2 3 >4 QDn/AuNR Figure 2...showing three-dimensional arrangement of the QOs around the AuNR. (e-i) Elemental mapping from STEM image of silica coated QD·AuNR architecture (e)(scale

String-averaging incremental subgradients for constrained convex optimization with applications to reconstruction of tomographic images

NASA Astrophysics Data System (ADS)

Massambone de Oliveira, Rafael; Salomão Helou, Elias; Fontoura Costa, Eduardo

2016-11-01

We present a method for non-smooth convex minimization which is based on subgradient directions and string-averaging techniques. In this approach, the set of available data is split into sequences (strings) and a given iterate is processed independently along each string, possibly in parallel, by an incremental subgradient method (ISM). The end-points of all strings are averaged to form the next iterate. The method is useful to solve sparse and large-scale non-smooth convex optimization problems, such as those arising in tomographic imaging. A convergence analysis is provided under realistic, standard conditions. Numerical tests are performed in a tomographic image reconstruction application, showing good performance for the convergence speed when measured as the decrease ratio of the objective function, in comparison to classical ISM.

SU-G-IeP4-08: Initial Investigations of Up-Converting Nanoparticles (UCNP) for 3D Tissue Imaging in Optical-ECT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoon, S; Dewhirst, M; Oldham, M

Purpose: Near-IR absorptive up-converting nanoparticles (UCNPs) is a novel contrast for optical-ECT that allows auto-fluorescence-free 3D imaging of labeled cells in a matrix of large (∼1cm{sup 3}) unsectioned normal tissue. This has the potential to image small metastases or dormant cells that is difficult with down-converting fluorescing dyes due to auto-fluorescence. The feasibility of imaging UCNP in agarose phantoms and a mouse lung is demonstrated, aided by a 3D-printed optical-ECT stage designed to excite UCNP in a mouse lung. Methods: The UCNP, NaYF{sub 4}:Yb/Er (20/2%), studied in this work up-converts 980nm light to visible light peaking sharply at ∼540nm. Tomore » characterize the UCNP emission as a function of UCNP concentration, cylindrical 2.5%wt agarose phantoms infused with UCNP at concentrations of 25µg/mL and 50µg/mL were exposed to 1.5W 980nm laser coupled to an optical fiber. The fiber was held stably at 1cm above the stage via a custom 3D-printed stage. An optically cleared lung harvested from a BALBc mice was then injected with 100µL of 1mg/mL UCNP solution ex vivo. Tomographic imaging of the UCNP emission in lung was performed. Results: The laser beam tract is visualized within the agarose phantom. A line profile of UCNP emission at 25µg/mL versus 50µg/mL shows that increasing the UCNP concentration increases emission count. UCNPs injected into a cleared mouse lung disperse throughout the respiratory tract, allowing for visualization and 3D reconstruction. Excitation before and after UCNP injection shows the tissue exhibits no auto-fluorescence at 980nm, allowing clear view of the UCNP without any obscuring features such as conventional down-converting fluorescent tags. Conclusion: We confirm that up-conversion in tissue circumvents completely tissue auto-fluorescence, which allowed background-free 3D reconstruction of the UCNP distribution. We also confirm that raising the UCNP concentration increases emission and that UCNPs are retained in agarose samples during the optical clearing process.« less

A PC-controlled microwave tomographic scanner for breast imaging

NASA Astrophysics Data System (ADS)

Padhi, Shantanu; Howard, John; Fhager, A.; Bengtsson, Sebastian

2011-01-01

This article presents the design and development of a personal computer based controller for a microwave tomographic system for breast cancer detection. The system uses motorized, dual-polarized antennas and a custom-made GUI interface to control stepper motors, a wideband vector network analyzer (VNA) and to coordinate data acquisition and archival in a local MDSPlus database. Both copolar and cross-polar scattered field components can be measured directly. Experimental results are presented to validate the various functionalities of the scanner.

Nuclear test ban treaty verification: Improving test ban monitoring with empirical and model-based signal processing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harris, David B.; Gibbons, Steven J.; Rodgers, Arthur J.

In this approach, small scale-length medium perturbations not modeled in the tomographic inversion might be described as random fields, characterized by particular distribution functions (e.g., normal with specified spatial covariance). Conceivably, random field parameters (scatterer density or scale length) might themselves be the targets of tomographic inversions of the scattered wave field. As a result, such augmented models may provide processing gain through the use of probabilistic signal sub spaces rather than deterministic waveforms.

Nuclear test ban treaty verification: Improving test ban monitoring with empirical and model-based signal processing

DOE PAGES

Harris, David B.; Gibbons, Steven J.; Rodgers, Arthur J.; ...

2012-05-01

In this approach, small scale-length medium perturbations not modeled in the tomographic inversion might be described as random fields, characterized by particular distribution functions (e.g., normal with specified spatial covariance). Conceivably, random field parameters (scatterer density or scale length) might themselves be the targets of tomographic inversions of the scattered wave field. As a result, such augmented models may provide processing gain through the use of probabilistic signal sub spaces rather than deterministic waveforms.

Medical tomograph system using ultrasonic transmission

NASA Technical Reports Server (NTRS)

Heyser, Richard C. (Inventor); Nathan, Robert (Inventor)

1978-01-01

Ultrasonic energy transmission in rectilinear array scanning patterns of soft tissue provides projection density values of the tissue which are recorded as a function of scanning position and angular relationship, .theta., of the subject with a fixed coordinate system. A plurality of rectilinear scan arrays in the same plane for different angular relationships .theta..sub.1 . . . .theta..sub.n thus recorded are superimposed. The superimposition of intensity values thus yields a tomographic image of an internal section of the tissue in the scanning plane.

Singular value decomposition: a diagnostic tool for ill-posed inverse problems in optical computed tomography

NASA Astrophysics Data System (ADS)

Lanen, Theo A.; Watt, David W.

1995-10-01

Singular value decomposition has served as a diagnostic tool in optical computed tomography by using its capability to provide insight into the condition of ill-posed inverse problems. Various tomographic geometries are compared to one another through the singular value spectrum of their weight matrices. The number of significant singular values in the singular value spectrum of a weight matrix is a quantitative measure of the condition of the system of linear equations defined by a tomographic geometery. The analysis involves variation of the following five parameters, characterizing a tomographic geometry: 1) the spatial resolution of the reconstruction domain, 2) the number of views, 3) the number of projection rays per view, 4) the total observation angle spanned by the views, and 5) the selected basis function. Five local basis functions are considered: the square pulse, the triangle, the cubic B-spline, the Hanning window, and the Gaussian distribution. Also items like the presence of noise in the views, the coding accuracy of the weight matrix, as well as the accuracy of the accuracy of the singular value decomposition procedure itself are assessed.

A Novel Quantitative Computed Tomographic Analysis Suggests How Sirolimus Stabilizes Progressive Air Trapping in Lymphangioleiomyomatosis

PubMed Central

Kokosi, Maria; Lo, Pechin; Kim, Hyun J.; Ravenel, James G.; Meyer, Cristopher; Goldin, Jonathan; Lee, Hye-Seung; Strange, Charlie; McCormack, Francis X.

2016-01-01

Rationale: The Multicenter International Lymphangioleiomyomatosis Efficacy and Safety of Sirolimus (MILES) trial demonstrated that sirolimus stabilized lung function and improved measures of functional performance and quality of life in patients with lymphangioleiomyomatosis. The physiologic mechanisms of these beneficial actions of sirolimus are incompletely understood. Objectives: To prospectively determine the longitudinal computed tomographic lung imaging correlates of lung function change in MILES patients treated with placebo or sirolimus. Methods: We determined the baseline to 12-month change in computed tomographic image–derived lung volumes and the volume of the lung occupied by cysts in the 31 MILES participants (17 in sirolimus group, 14 in placebo group) with baseline and 12-month scans. Measurements and Main Results: There was a trend toward an increase in median expiratory cyst volume percentage in the placebo group and a reduction in the sirolimus group (+2.68% vs. +0.97%, respectively; P = 0.10). The computed tomographic image–derived residual volume and the ratio of residual volume to total lung capacity increased more in the placebo group than in the sirolimus group (+214.4 ml vs. +2.9 ml [P = 0.054] and +0.05 ml vs. −0.01 ml [P = 0.0498], respectively). A Markov transition chain analysis of respiratory cycle cyst volume changes revealed greater dynamic variation in the sirolimus group than in the placebo group at the 12-month time point. Conclusions: Collectively, these data suggest that sirolimus attenuates progressive gas trapping in lymphangioleiomyomatosis, consistent with a beneficial effect of the drug on airflow obstruction. We speculate that a reduction in lymphangioleiomyomatosis cell burden around small airways and cyst walls alleviates progressive airflow limitation and facilitates cyst emptying. PMID:26799509

A Novel Quantitative Computed Tomographic Analysis Suggests How Sirolimus Stabilizes Progressive Air Trapping in Lymphangioleiomyomatosis.

PubMed

Argula, Rahul G; Kokosi, Maria; Lo, Pechin; Kim, Hyun J; Ravenel, James G; Meyer, Cristopher; Goldin, Jonathan; Lee, Hye-Seung; Strange, Charlie; McCormack, Francis X

2016-03-01

The Multicenter International Lymphangioleiomyomatosis Efficacy and Safety of Sirolimus (MILES) trial demonstrated that sirolimus stabilized lung function and improved measures of functional performance and quality of life in patients with lymphangioleiomyomatosis. The physiologic mechanisms of these beneficial actions of sirolimus are incompletely understood. To prospectively determine the longitudinal computed tomographic lung imaging correlates of lung function change in MILES patients treated with placebo or sirolimus. We determined the baseline to 12-month change in computed tomographic image-derived lung volumes and the volume of the lung occupied by cysts in the 31 MILES participants (17 in sirolimus group, 14 in placebo group) with baseline and 12-month scans. There was a trend toward an increase in median expiratory cyst volume percentage in the placebo group and a reduction in the sirolimus group (+2.68% vs. +0.97%, respectively; P = 0.10). The computed tomographic image-derived residual volume and the ratio of residual volume to total lung capacity increased more in the placebo group than in the sirolimus group (+214.4 ml vs. +2.9 ml [P = 0.054] and +0.05 ml vs. -0.01 ml [P = 0.0498], respectively). A Markov transition chain analysis of respiratory cycle cyst volume changes revealed greater dynamic variation in the sirolimus group than in the placebo group at the 12-month time point. Collectively, these data suggest that sirolimus attenuates progressive gas trapping in lymphangioleiomyomatosis, consistent with a beneficial effect of the drug on airflow obstruction. We speculate that a reduction in lymphangioleiomyomatosis cell burden around small airways and cyst walls alleviates progressive airflow limitation and facilitates cyst emptying.

Influence of the limited detector size on spatial variations of the reconstruction accuracy in holographic tomography

NASA Astrophysics Data System (ADS)

Kostencka, Julianna; Kozacki, Tomasz; Hennelly, Bryan; Sheridan, John T.

2017-06-01

Holographic tomography (HT) allows noninvasive, quantitative, 3D imaging of transparent microobjects, such as living biological cells and fiber optics elements. The technique is based on acquisition of multiple scattered fields for various sample perspectives using digital holographic microscopy. Then, the captured data is processed with one of the tomographic reconstruction algorithms, which enables 3D reconstruction of refractive index distribution. In our recent works we addressed the issue of spatially variant accuracy of the HT reconstructions, which results from the insufficient model of diffraction that is applied in the widely-used tomographic reconstruction algorithms basing on the Rytov approximation. In the present study, we continue investigating the spatially variant properties of the HT imaging, however, we are now focusing on the limited spatial size of holograms as a source of this problem. Using the Wigner distribution representation and the Ewald sphere approach, we show that the limited size of the holograms results in a decreased quality of tomographic imaging in off-center regions of the HT reconstructions. This is because the finite detector extent becomes a limiting aperture that prohibits acquisition of full information about diffracted fields coming from the out-of-focus structures of a sample. The incompleteness of the data results in an effective truncation of the tomographic transfer function for the out-of-center regions of the tomographic image. In this paper, the described effect is quantitatively characterized for three types of the tomographic systems: the configuration with 1) object rotation, 2) scanning of the illumination direction, 3) the hybrid HT solution combing both previous approaches.

A three-dimensional strain measurement method in elastic transparent materials using tomographic particle image velocimetry

PubMed Central

Suzuki, Sara; Aoyama, Yusuke; Umezu, Mitsuo

2017-01-01

Background The mechanical interaction between blood vessels and medical devices can induce strains in these vessels. Measuring and understanding these strains is necessary to identify the causes of vascular complications. This study develops a method to measure the three-dimensional (3D) distribution of strain using tomographic particle image velocimetry (Tomo-PIV) and compares the measurement accuracy with the gauge strain in tensile tests. Methods and findings The test system for measuring 3D strain distribution consists of two cameras, a laser, a universal testing machine, an acrylic chamber with a glycerol water solution for adjusting the refractive index with the silicone, and dumbbell-shaped specimens mixed with fluorescent tracer particles. 3D images of the particles were reconstructed from 2D images using a multiplicative algebraic reconstruction technique (MART) and motion tracking enhancement. Distributions of the 3D displacements were calculated using a digital volume correlation. To evaluate the accuracy of the measurement method in terms of particle density and interrogation voxel size, the gauge strain and one of the two cameras for Tomo-PIV were used as a video-extensometer in the tensile test. The results show that the optimal particle density and interrogation voxel size are 0.014 particles per pixel and 40 × 40 × 40 voxels with a 75% overlap. The maximum measurement error was maintained at less than 2.5% in the 4-mm-wide region of the specimen. Conclusions We successfully developed a method to experimentally measure 3D strain distribution in an elastic silicone material using Tomo-PIV and fluorescent particles. To the best of our knowledge, this is the first report that applies Tomo-PIV to investigate 3D strain measurements in elastic materials with large deformation and validates the measurement accuracy. PMID:28910397

Fluence compensated photoacoustic tomography in small animals (Conference Presentation)

NASA Astrophysics Data System (ADS)

Hussain, Altaf; Pool, Martin; Daoudi, Khalid; de Vries, Liesbeth G.; Steenbergen, Wiendelt

2017-03-01

Light fluence inside turbid media can be experimentally mapped by measuring ultrasonically modulated light (Acousto-optics). To demonstrate the feasibility of fluence corrected Photoacoustic (PA) imaging, we have realized a tri-modality (i.e. photoacoustic, acousto-optic and ultrasound) tomographic small animal imaging system. Wherein PA imaging provides high resolution map of absorbed optical energy density, Acousto-optics yields the fluence distribution map in the corresponding PA imaging plane and Ultrasound provides morphological information. Further, normalization of the PA image with the acousto-optically measured fluence map results in an image that directly represents the optical absorption. Human epidermal growth factor receptor 2 (HER2) is commonly found overexpressed in human cancers, among which breast cancers, resulting in a more aggressive tumor phenotype. Identification of HER2-expression is clinically relevant, because cancers overexpressing this marker are amenable to HER2-directed therapies, among which antibodies trastuzumab and pertuzumab. Here, we investigate the feasibility and advantage of acousto-optically assisted fluence compensated PA imaging over PA imaging alone in visualizing and quantifying HER2 expression. For this experiment, nude mice were xenografted with human breast cancer cell lines SKBR3 and BT474 (both HER2 overexpressing), as well as HER2-negative MDA-MB-231. To visualize HER2 expression in these mice, HER2 monoclonal antibody pertuzumab (Perjeta®, Roche), was conjugated to near-infrared dye IRDye 800CW (800CW, LICOR Biosciences) at a ratio of 1∶2 antibody to 800CW. When xenograft tumors measured ≥ 100 mm3, mice received 100 µg 800CW-pertuzumab intravenously. Three days post injection, mice were scanned for fluorescence signal with an IVIS scanner. After fluorescence scans, mice were euthanized and imaged in our PA tomographic imaging system.

Estimating crustal heterogeneity from double-difference tomography

USGS Publications Warehouse

Got, J.-L.; Monteiller, V.; Virieux, J.; Okubo, P.

2006-01-01

Seismic velocity parameters in limited, but heterogeneous volumes can be inferred using a double-difference tomographic algorithm, but to obtain meaningful results accuracy must be maintained at every step of the computation. MONTEILLER et al. (2005) have devised a double-difference tomographic algorithm that takes full advantage of the accuracy of cross-spectral time-delays of large correlated event sets. This algorithm performs an accurate computation of theoretical travel-time delays in heterogeneous media and applies a suitable inversion scheme based on optimization theory. When applied to Kilauea Volcano, in Hawaii, the double-difference tomography approach shows significant and coherent changes to the velocity model in the well-resolved volumes beneath the Kilauea caldera and the upper east rift. In this paper, we first compare the results obtained using MONTEILLER et al.'s algorithm with those obtained using the classic travel-time tomographic approach. Then, we evaluated the effect of using data series of different accuracies, such as handpicked arrival-time differences ("picking differences"), on the results produced by double-difference tomographic algorithms. We show that picking differences have a non-Gaussian probability density function (pdf). Using a hyperbolic secant pdf instead of a Gaussian pdf allows improvement of the double-difference tomographic result when using picking difference data. We completed our study by investigating the use of spatially discontinuous time-delay data. ?? Birkha??user Verlag, Basel, 2006.

Instrumentation of Molecular Imaging on Site-Specific Targeting Fluorescent Peptide for Early Detection of Breast Cancer

NASA Astrophysics Data System (ADS)

Yu, Ping; Ma, Lixin

2012-02-01

In this work we developed two biomedical imaging techniques for early detection of breast cancer. Both image modalities provide molecular imaging capability to probe site-specific targeting dyes. The first technique, heterodyne CCD fluorescence mediated tomography, is a non-invasive biomedical imaging that uses fluorescent photons from the targeted dye on the tumor cells inside human breast tissue. The technique detects a large volume of tissue (20 cm) with a moderate resolution (1 mm) and provides the high sensitivity. The second technique, dual-band spectral-domain optical coherence tomography, is a high-resolution tissue imaging modality. It uses a low coherence interferometer to detect coherent photons hidden in the incoherent background. Due to the coherence detection, a high resolution (20 microns) is possible. We have finished prototype imaging systems for the development of both image modalities and performed imaging experiments on tumor tissues. The spectroscopic/tomographic images show contrasts of dense tumor tissues and tumor necrotic regions. In order to correlate the findings from our results, a diffusion-weighted magnetic resonance imaging (MRI) of the tumors was performed using a small animal 7-Telsa MRI and demonstrated excellent agreement.

Clinical studies of pigmented lesions in human skin by using a multiphoton tomograph

NASA Astrophysics Data System (ADS)

Balu, Mihaela; Kelly, Kristen M.; Zachary, Christopher B.; Harris, Ronald M.; Krasieva, Tatiana B.; König, Karsten; Tromberg, Bruce J.

2013-02-01

In vivo imaging of pigmented lesions in human skin was performed with a clinical multiphoton microscopy (MPM)-based tomograph (MPTflex, JenLab, Germany). Two-photon excited fluorescence was used for visualizing endogenous fluorophores such as NADH/FAD, keratin, melanin in the epidermal cells and elastin fibers in the dermis. Collagen fibers were imaged by second harmonic generation. Our study involved in vivo imaging of benign melanocytic nevi, atypical nevi and melanoma. The goal of this preliminary study was to identify in vivo the characteristic features and their frequency in pigmented lesions at different stages (benign, atypical and malignant) and to evaluate the ability of in vivo MPM to distinguish atypical nevi from melanoma. Comparison with histopathology was performed for the biopsied lesions. Benign melanocytic nevi were characterized by the presence of nevus cell nests at the epidermal-dermal junction. In atypical nevi, features such as lentiginous hyperplasia, acanthosis and architectural disorder were imaged. Cytological atypia was present in all the melanoma lesions imaged, showing the strongest correlation with malignancy. The MPM images demonstrated very good correlation with corresponding histological images, suggesting that MPM could be a promising tool for in vivo non-invasive pigmented lesion diagnosis, particularly distinguishing atypical nevi from melanoma.

Correlative cryo-fluorescence light microscopy and cryo-electron tomography of Streptomyces.

PubMed

Koning, Roman I; Celler, Katherine; Willemse, Joost; Bos, Erik; van Wezel, Gilles P; Koster, Abraham J

2014-01-01

Light microscopy and electron microscopy are complementary techniques that in a correlative approach enable identification and targeting of fluorescently labeled structures in situ for three-dimensional imaging at nanometer resolution. Correlative imaging allows electron microscopic images to be positioned in a broader temporal and spatial context. We employed cryo-correlative light and electron microscopy (cryo-CLEM), combining cryo-fluorescence light microscopy and cryo-electron tomography, on vitrified Streptomyces bacteria to study cell division. Streptomycetes are mycelial bacteria that grow as long hyphae and reproduce via sporulation. On solid media, Streptomyces subsequently form distinct aerial mycelia where cell division leads to the formation of unigenomic spores which separate and disperse to form new colonies. In liquid media, only vegetative hyphae are present divided by noncell separating crosswalls. Their multicellular life style makes them exciting model systems for the study of bacterial development and cell division. Complex intracellular structures have been visualized with transmission electron microscopy. Here, we describe the methods for cryo-CLEM that we applied for studying Streptomyces. These methods include cell growth, fluorescent labeling, cryo-fixation by vitrification, cryo-light microscopy using a Linkam cryo-stage, image overlay and relocation, cryo-electron tomography using a Titan Krios, and tomographic reconstruction. Additionally, methods for segmentation, volume rendering, and visualization of the correlative data are described. © 2014 Elsevier Inc. All rights reserved.

Numerical Simulations to Assess ART and MART Performance for Ionospheric Tomography of Chapman Profiles.

PubMed

Prol, Fabricio S; Camargo, Paulo O; Muella, Marcio T A H

2017-01-01

The incomplete geometrical coverage of the Global Navigation Satellite System (GNSS) makes the ionospheric tomographic system an ill-conditioned problem for ionospheric imaging. In order to detect the principal limitations of the ill-conditioned tomographic solutions, numerical simulations of the ionosphere are under constant investigation. In this paper, we show an investigation of the accuracy of Algebraic Reconstruction Technique (ART) and Multiplicative ART (MART) for performing tomographic reconstruction of Chapman profiles using a simulated optimum scenario of GNSS signals tracked by ground-based receivers. Chapman functions were used to represent the ionospheric morphology and a set of analyses was conducted to assess ART and MART performance for estimating the Total Electron Content (TEC) and parameters that describes the Chapman function. The results showed that MART performed better in the reconstruction of the electron density peak and ART gave a better representation for estimating TEC and the shape of the ionosphere. Since we used an optimum scenario of the GNSS signals, the analyses indicate the intrinsic problems that may occur with ART and MART to recover valuable information for many applications of Telecommunication, Spatial Geodesy and Space Weather.

A three-step reconstruction method for fluorescence molecular tomography based on compressive sensing

NASA Astrophysics Data System (ADS)

Zhu, Yansong; Jha, Abhinav K.; Dreyer, Jakob K.; Le, Hanh N. D.; Kang, Jin U.; Roland, Per E.; Wong, Dean F.; Rahmim, Arman

2017-02-01

Fluorescence molecular tomography (FMT) is a promising tool for real time in vivo quantification of neurotransmission (NT) as we pursue in our BRAIN initiative effort. However, the acquired image data are noisy and the reconstruction problem is ill-posed. Further, while spatial sparsity of the NT effects could be exploited, traditional compressive-sensing methods cannot be directly applied as the system matrix in FMT is highly coherent. To overcome these issues, we propose and assess a three-step reconstruction method. First, truncated singular value decomposition is applied on the data to reduce matrix coherence. The resultant image data are input to a homotopy-based reconstruction strategy that exploits sparsity via l1 regularization. The reconstructed image is then input to a maximum-likelihood expectation maximization (MLEM) algorithm that retains the sparseness of the input estimate and improves upon the quantitation by accurate Poisson noise modeling. The proposed reconstruction method was evaluated in a three-dimensional simulated setup with fluorescent sources in a cuboidal scattering medium with optical properties simulating human brain cortex (reduced scattering coefficient: 9.2 cm-1, absorption coefficient: 0.1 cm-1 and tomographic measurements made using pixelated detectors. In different experiments, fluorescent sources of varying size and intensity were simulated. The proposed reconstruction method provided accurate estimates of the fluorescent source intensity, with a 20% lower root mean square error on average compared to the pure-homotopy method for all considered source intensities and sizes. Further, compared with conventional l2 regularized algorithm, overall, the proposed method reconstructed substantially more accurate fluorescence distribution. The proposed method shows considerable promise and will be tested using more realistic simulations and experimental setups.

A 3D gantry single photon emission tomograph with hemispherical coverage for dedicated breast imaging

NASA Astrophysics Data System (ADS)

Tornai, Martin P.; Bowsher, James E.; Archer, Caryl N.; Peter, Jörg; Jaszczak, Ronald J.; MacDonald, Lawrence R.; Patt, Bradley E.; Iwanczyk, Jan S.

2003-01-01

A novel tomographic gantry was designed, built and initially evaluated for single photon emission imaging of metabolically active lesions in the pendant breast and near chest wall. Initial emission imaging measurements with breast lesions of various uptake ratios are presented. Methods: A prototype tomograph was constructed utilizing a compact gamma camera having a field-of-view of <13×13 cm 2 with arrays of 2×2×6 mm 3 quantized NaI(Tl) scintillators coupled to position sensitive PMTs. The camera was mounted on a radially oriented support with 6 cm variable radius-of-rotation. This unit is further mounted on a goniometric cradle providing polar motion, and in turn mounted on an azimuthal rotation stage capable of indefinite vertical axis-of-rotation about the central rotation axis (RA). Initial measurements with isotopic Tc-99 m (140 keV) to evaluate the system include acquisitions with various polar tilt angles about the RA. Tomographic measurements were made of a frequency and resolution cold-rod phantom filled with aqueous Tc-99 m. Tomographic and planar measurements of 0.6 and 1.0 cm diameter fillable spheres in an available ˜950 ml hemi-ellipsoidal (uncompressed) breast phantom attached to a life-size anthropomorphic torso phantom with lesion:breast-and-body:cardiac-and-liver activity concentration ratios of 11:1:19 were compared. Various photopeak energy windows from 10-30% widths were obtained, along with a 35% scatter window below a 15% photopeak window from the list mode data. Projections with all photopeak window and camera tilt conditions were reconstructed with an ordered subsets expectation maximization (OSEM) algorithm capable of reconstructing arbitrary tomographic orbits. Results: As iteration number increased for the tomographically measured data at all polar angles, contrasts increased while signal-to-noise ratios (SNRs) decreased in the expected way with OSEM reconstruction. The rollover between contrast improvement and SNR degradation of the lesion occurred at two to three iterations. The reconstructed tomographic data yielded SNRs with or without scatter correction that were >9 times better than the planar scans. There was up to a factor of ˜2.5 increase in total primary and scatter contamination in the photopeak window with increasing tilt angle from 15° to 45°, consistent with more direct line-of-sight of myocardial and liver activity with increased camera polar angle. Conclusion: This new, ultra-compact, dedicated tomographic imaging system has the potential of providing valuable, fully 3D functional information about small, otherwise indeterminate breast lesions as an adjunct to diagnostic mammography.

Preliminary study on X-ray fluorescence computed tomography imaging of gold nanoparticles: Acceleration of data acquisition by multiple pinholes scheme

NASA Astrophysics Data System (ADS)

Sasaya, Tenta; Sunaguchi, Naoki; Seo, Seung-Jum; Hyodo, Kazuyuki; Zeniya, Tsutomu; Kim, Jong-Ki; Yuasa, Tetsuya

2018-04-01

Gold nanoparticles (GNPs) have recently attracted attention in nanomedicine as novel contrast agents for cancer imaging. A decisive tomographic imaging technique has not yet been established to depict the 3-D distribution of GNPs in an object. An imaging technique known as pinhole-based X-ray fluorescence computed tomography (XFCT) is a promising method that can be used to reconstruct the distribution of GNPs from the X-ray fluorescence emitted by GNPs. We address the acceleration of data acquisition in pinhole-based XFCT for preclinical use using a multiple pinhole scheme. In this scheme, multiple projections are simultaneously acquired through a multi-pinhole collimator with a 2-D detector and full-field volumetric beam to enhance the signal-to-noise ratio of the projections; this enables fast data acquisition. To demonstrate the efficacy of this method, we performed an imaging experiment using a physical phantom with an actual multi-pinhole XFCT system that was constructed using the beamline AR-NE7A at KEK. The preliminary study showed that the multi-pinhole XFCT achieved a data acquisition time of 20 min at a theoretical detection limit of approximately 0.1 Au mg/ml and at a spatial resolution of 0.4 mm.

Multiphoton autofluorescence lifetime imaging of induced pluripotent stem cells

NASA Astrophysics Data System (ADS)

Uchugonova, Aisada

2017-06-01

The multiphoton fluorescence lifetime imaging tomograph MPTflex with its flexible 360-deg scan head, articulated arm, and tunable femtosecond laser source was employed to study induced pluripotent stem cell (iPS) cultures. Autofluorescence (AF) lifetime imaging was performed with 250-ps temporal resolution and submicron spatial resolution using time-correlated single-photon counting. The two-photon excited AF was based on the metabolic coenzymes NAD(P)H and flavin adenine dinucleotide/flavoproteins. iPS cells generated from mouse embryonic fibroblasts (MEFs) and cocultured with growth-arrested MEFs as feeder cells have been studied. Significant differences on AF lifetime signatures were identified between iPS and feeder cells as well as between their differentiating counterparts.

Dynamic Computed Tomographic Features of Adult Renal Cell Carcinoma Associated With Xp11.2 Translocation/TFE3 Gene Fusions: Comparison With Clear Cell Renal Cell Carcinoma.

PubMed

He, Jian; Gan, Weidong; Liu, Song; Zhou, Kefeng; Zhang, Gutian; Guo, Hongqian; Zhu, Bin

2015-01-01

To investigate the dynamic contrast-enhanced computed tomography (CT) characteristics of renal cell carcinoma associated with Xp11.2 translocation and TFE gene fusion (Xp11.2 RCC) by comparison with clear cell renal cell carcinoma (CCRCC). Dynamic contrast-enhanced CT images and clinical and pathological records of 20 adult patients with Xp11.2 RCC confirmed by TFE3 immunohistochemical and fluorescence in situ hybridization assay were retrospectively analyzed and compared with the findings of 21 contemporary CCRCCs. Renal cell carcinoma associated with Xp11.2 translocation and TFE gene fusions often occurred in young (30.6 ± 8.6 years) patients with hematuria (9/20). They presented as well-defined (17/20) cystic-solid (17/20) mass with hemorrhage (8/20) and circular/rim calcifications (6/20). Dynamic contrast-enhanced CT showed heterogeneous moderate prolonged enhancement. A tumor-to-cortex attenuation ratio in corticomedullary phase less than 0.62 gave a sensitivity of 90.0% and a specificity of 92.9% in differentiating Xp11.2 RCC from CCRCC (area under the receiver operating characteristic curve = 0.957, P < 0.001). Computed tomographic characteristics and dynamic contrast-enhanced patterns and index can differentiate Xp11.2 RCC from CCRCC.

Three-dimensional DNA image cytometry by optical projection tomographic microscopy for early cancer diagnosis.

PubMed

Agarwal, Nitin; Biancardi, Alberto M; Patten, Florence W; Reeves, Anthony P; Seibel, Eric J

2014-04-01

Aneuploidy is typically assessed by flow cytometry (FCM) and image cytometry (ICM). We used optical projection tomographic microscopy (OPTM) for assessing cellular DNA content using absorption and fluorescence stains. OPTM combines some of the attributes of both FCM and ICM and generates isometric high-resolution three-dimensional (3-D) images of single cells. Although the depth of field of the microscope objective was in the submicron range, it was extended by scanning the objective's focal plane. The extended depth of field image is similar to a projection in a conventional x-ray computed tomography. These projections were later reconstructed using computed tomography methods to form a 3-D image. We also present an automated method for 3-D nuclear segmentation. Nuclei of chicken, trout, and triploid trout erythrocyte were used to calibrate OPTM. Ratios of integrated optical densities extracted from 50 images of each standard were compared to ratios of DNA indices from FCM. A comparison of mean square errors with thionin, hematoxylin, Feulgen, and SYTOX green was done. Feulgen technique was preferred as it showed highest stoichiometry, least variance, and preserved nuclear morphology in 3-D. The addition of this quantitative biomarker could further strengthen existing classifiers and improve early diagnosis of cancer using 3-D microscopy.

Spatio-Temporal Cellular Imaging of Polymer-pDNA Nanocomplexes Affords In Situ Morphology and Trafficking Trends

PubMed Central

Ingle, Nilesh P.; Lian, Xue; Reineke, Theresa M.

2013-01-01

Synthetic polymers are ubiquitous in the development of drug and polynucleotide delivery vehicles, offering promise for personalized medicine. However, the polymer structure plays a central yet elusive role in dictating the efficacy, safety, mechanisms, and kinetics of therapeutic transport in a spatial and temporal manner. Here, we decipher the intracellular evolutionary pathways pertaining to shape, size, location, and mechanism of four structurally-divergent polymer vehicles (Tr455, Tr477, jetPEI™ and Glycofect™) that create colloidal nanoparticles (polyplexes) when complexed with fluorescently-labeled plasmid DNA (pDNA). Multiple high resolution tomographic images of whole HeLa (human cervical adenocarcinoma) cells were captured via confocal microscopy at 4, 8, 12 and 24 hours. The images were reconstructed to visualize and quantify trends in situ in a four-dimensional spatio-temporal manner. The data revealed heretofore-unseen images of polyplexes in situ and structure-function relationships, i.e., Glycofect™ polyplexes are trafficked as the smallest polyplex complexes and Tr455 polyplexes have expedited translocation to the perinuclear region. Also, all of the polyplex types appeared to be preferentially internalized and trafficked via early endosomes affiliated with caveolae, a Rab-5-dependent pathway, actin, and microtubules. PMID:24007201

A small animal time-resolved optical tomography platform using wide-field excitation

NASA Astrophysics Data System (ADS)

Venugopal, Vivek

Small animal imaging plays a critical role in present day biomedical research by filling an important gap in the translation of research from the bench to the bedside. Optical techniques constitute an emerging imaging modality which have tremendous potential in preclinical applications. Optical imaging methods are capable of non-invasive assessment of the functional and molecular characteristics of biological tissue. The three-dimensional optical imaging technique, referred to as diffuse optical tomography, provides an approach for the whole-body imaging of small animal models and can provide volumetric maps of tissue functional parameters (e.g. blood volume, oxygen saturation etc.) and/or provide 3D localization and quantification of fluorescence-based molecular markers in vivo. However, the complex mathematical reconstruction problem associated with optical tomography and the cumbersome instrumental designs limits its adoption as a high-throughput quantitative whole-body imaging modality in current biomedical research. The development of new optical imaging paradigms is thus necessary for a wide-acceptance of this new technology. In this thesis, the design, development, characterization and optimization of a small animal optical tomography system is discussed. Specifically, the platform combines a highly sensitive time-resolved imaging paradigm with multi-spectral excitation capability and CCD-based detection to provide a system capable of generating spatially, spectrally and temporally dense measurement datasets. The acquisition of such data sets however can take long and translate to often unrealistic acquisition times when using the classical point source based excitation scheme. The novel approach in the design of this platform is the adoption of a wide-field excitation scheme which employs extended excitation sources and in the process allows an estimated ten-fold reduction in the acquisition time. The work described herein details the design of the imaging platform employing DLP-based excitation and time-gated intensified CCD detection and the optimal system operation parameters are determined. The feasibility this imaging approach and accuracy of the system in reconstructing functional parameters and fluorescence markers based on lifetime contrast is established through phantom studies. As a part of the system characterization, the effect of noise in time-resolved optical tomography is investigated and propagation of system noise in optical reconstructions is established. Furthermore, data processing and measurement calibration techniques aimed at reducing the effect of noise in reconstructions are defined. The optimization of excitation pattern selection is established through a novel measurement-guided iterative pattern correction scheme. This technique referred to as Adaptive Full-Field Optical Tomography was shown to improve reconstruction performances in murine models by reducing the dynamic range in photon flux measurements on the surface. Lastly, the application of the unique attributes of this platform to a biologically relevant imaging application, referred to as Forster Resonance Energy Transfer is described. The tomographic imaging of FRET interaction in vivo on a whole-body scale is achieved using the wide-field imaging approach based on lifetime contrast. This technique represents the first demonstration of tomographic FRET imaging in small animals and has significant potential in the development of optical imaging techniques in varied applications ranging from drug discovery to in vivo study of protein-protein interaction.

Resting-state functional connectivity assessed with two diffuse optical tomographic systems.

PubMed

Niu, Haijing; Khadka, Sabin; Tian, Fenghua; Lin, Zi-Jing; Lu, Chunming; Zhu, Chaozhe; Liu, Hanli

2011-04-01

Functional near-infrared spectroscopy (fNIRS) is recently utilized as a new approach to assess resting-state functional connectivity (RSFC) in the human brain. For any new technique or new methodology, it is necessary to be able to replicate similar experiments using different instruments in order to establish its liability and reproducibility. We apply two different diffuse optical tomographic (DOT) systems (i.e., DYNOT and CW5), with various probe arrangements to evaluate RSFC in the sensorimotor cortex by utilizing a previously published experimental protocol and seed-based correlation analysis. Our results exhibit similar spatial patterns and strengths in RSFC between the bilateral motor cortexes. The consistent observations are obtained from both DYNOT and CW5 systems, and are also in good agreement with the previous fNIRS study. Overall, we demonstrate that the fNIRS-based RSFC is reproducible by various DOT imaging systems among different research groups, enhancing the confidence of neuroscience researchers and clinicians to utilize fNIRS for future applications.

Inspiratory and expiratory computed tomographic volumetry for lung volume reduction surgery.

PubMed

Morimura, Yuki; Chen, Fengshi; Sonobe, Makoto; Date, Hiroshi

2013-06-01

Three-dimensional (3D) computed tomographic (CT) volumetry has been introduced into the field of thoracic surgery, and a combination of inspiratory and expiratory 3D-CT volumetry provides useful data on regional pulmonary function as well as the volume of individual lung lobes. We report herein a case of a 62-year-old man with severe emphysema who had undergone lung volume reduction surgery (LVRS) to assess this technique as a tool for the evaluation of regional lung function and volume before and after LVRS. His postoperative pulmonary function was maintained in good condition despite a gradual slight decrease 2 years after LVRS. This trend was also confirmed by a combination of inspiratory and expiratory 3D-CT volumetry. We confirm that a combination of inspiratory and expiratory 3D-CT volumetry might be effective for the preoperative assessment of LVRS in order to determine the amount of lung tissue to be resected as well as for postoperative evaluation. This novel technique could, therefore, be used more widely to assess local lung function.

Inspiratory and expiratory computed tomographic volumetry for lung volume reduction surgery

PubMed Central

Morimura, Yuki; Chen, Fengshi; Sonobe, Makoto; Date, Hiroshi

2013-01-01

Three-dimensional (3D) computed tomographic (CT) volumetry has been introduced into the field of thoracic surgery, and a combination of inspiratory and expiratory 3D-CT volumetry provides useful data on regional pulmonary function as well as the volume of individual lung lobes. We report herein a case of a 62-year-old man with severe emphysema who had undergone lung volume reduction surgery (LVRS) to assess this technique as a tool for the evaluation of regional lung function and volume before and after LVRS. His postoperative pulmonary function was maintained in good condition despite a gradual slight decrease 2 years after LVRS. This trend was also confirmed by a combination of inspiratory and expiratory 3D-CT volumetry. We confirm that a combination of inspiratory and expiratory 3D-CT volumetry might be effective for the preoperative assessment of LVRS in order to determine the amount of lung tissue to be resected as well as for postoperative evaluation. This novel technique could, therefore, be used more widely to assess local lung function. PMID:23460599

Distinct constrictive processes, separated in time and space, divide caulobacter inner and outer membranes.

PubMed

Judd, Ellen M; Comolli, Luis R; Chen, Joseph C; Downing, Kenneth H; Moerner, W E; McAdams, Harley H

2005-10-01

Cryoelectron microscope tomography (cryoEM) and a fluorescence loss in photobleaching (FLIP) assay were used to characterize progression of the terminal stages of Caulobacter crescentus cell division. Tomographic cryoEM images of the cell division site show separate constrictive processes closing first the inner membrane (IM) and then the outer membrane (OM) in a manner distinctly different from that of septum-forming bacteria. FLIP experiments had previously shown cytoplasmic compartmentalization (when cytoplasmic proteins can no longer diffuse between the two nascent progeny cell compartments) occurring 18 min before daughter cell separation in a 135-min cell cycle so the two constrictive processes are separated in both time and space. In the very latest stages of both IM and OM constriction, short membrane tether structures are observed. The smallest observed pre-fission tethers were 60 nm in diameter for both the inner and outer membranes. Here, we also used FLIP experiments to show that both membrane-bound and periplasmic fluorescent proteins diffuse freely through the FtsZ ring during most of the constriction procession.

Multiphoton tomography of astronauts

NASA Astrophysics Data System (ADS)

König, Karsten; Weinigel, Martin; Pietruszka, Anna; Bückle, Rainer; Gerlach, Nicole; Heinrich, Ulrike

2015-03-01

Weightlessness may impair the astronaut's health conditions. Skin impairments belong to the most frequent health problems during space missions. Within the Skin B project, skin physiological changes during long duration space flights are currently investigated on three European astronauts that work for nearly half a year at the ISS. Measurements on the hydration, the transepidermal water loss, the surface structure, elasticity and the tissue density by ultrasound are conducted. Furthermore, high-resolution in vivo histology is performed by multiphoton tomography with 300 nm spatial and 200 ps temporal resolution. The mobile certified medical tomograph with a flexible 360° scan head attached to a mechano-optical arm is employed to measure two-photon autofluorescence and SHG in the volar forearm of the astronauts. Modification of the tissue architecture and of the fluorescent biomolecules NAD(P)H, keratin, melanin and elastin are detected as well as of SHG-active collagen. Thinning of the vital epidermis, a decrease of the autofluoresence intensity, an increase in the long fluorescence lifetime, and a reduced skin ageing index SAAID based on an increased collagen level in the upper dermis have been found. Current studies focus on recovery effects.

Laboratory Scale X-ray Fluorescence Tomography: Instrument Characterization and Application in Earth and Environmental Science.

PubMed

Laforce, Brecht; Vermeulen, Bram; Garrevoet, Jan; Vekemans, Bart; Van Hoorebeke, Luc; Janssen, Colin; Vincze, Laszlo

2016-03-15

A new laboratory scale X-ray fluorescence (XRF) imaging instrument, based on an X-ray microfocus tube equipped with a monocapillary optic, has been developed to perform XRF computed tomography experiments with both higher spatial resolution (20 μm) and a better energy resolution (130 eV @Mn-K(α)) than has been achieved up-to-now. This instrument opens a new range of possible applications for XRF-CT. Next to the analytical characterization of the setup by using well-defined model/reference samples, demonstrating its capabilities for tomographic imaging, the XRF-CT microprobe has been used to image the interior of an ecotoxicological model organism, Americamysis bahia. This had been exposed to elevated metal (Cu and Ni) concentrations. The technique allowed the visualization of the accumulation sites of copper, clearly indicating the affected organs, i.e. either the gastric system or the hepatopancreas. As another illustrative application, the scanner has been employed to investigate goethite spherules from the Cretaceous-Paleogene boundary, revealing the internal elemental distribution of these valuable distal ejecta layer particles.

Ambient Noise Interferometry and Surface Wave Array Tomography: Promises and Problems

NASA Astrophysics Data System (ADS)

van der Hilst, R. D.; Yao, H.; de Hoop, M. V.; Campman, X.; Solna, K.

2008-12-01

In the late 1990ies most seismologists would have frowned at the possibility of doing high-resolution surface wave tomography with noise instead of with signal associated with ballistic source-receiver propagation. Some may still do, but surface wave tomography with Green's functions estimated through ambient noise interferometry ('sourceless tomography') has transformed from a curiosity into one of the (almost) standard tools for analysis of data from dense seismograph arrays. Indeed, spectacular applications of ambient noise surface wave tomography have recently been published. For example, application to data from arrays in SE Tibet revealed structures in the crust beneath the Tibetan plateau that could not be resolved by traditional tomography (Yao et al., GJI, 2006, 2008). While the approach is conceptually simple, in application the proverbial devil is in the detail. Full reconstruction of the Green's function requires that the wavefields used are diffusive and that ambient noise energy is evenly distributed in the spatial dimensions of interest. In the field, these conditions are not usually met, and (frequency dependent) non-uniformity of the noise sources may lead to incomplete reconstruction of the Green's function. Furthermore, ambient noise distributions can be time-dependent, and seasonal variations have been documented. Naive use of empirical Green's functions may produce (unknown) bias in the tomographic models. The degrading effect on EGFs of the directionality of noise distribution forms particular challenges for applications beyond isotropic surface wave inversions, such as inversions for (azimuthal) anisotropy and attempts to use higher modes (or body waves). Incomplete Green's function reconstruction can (probably) not be prevented, but it may be possible to reduce the problem and - at least - understand the degree of incomplete reconstruction and prevent it from degrading the tomographic model. We will present examples of Rayleigh wave inversions and discuss strategies to mitigate effects of incomplete Green's function reconstruction on tomographic images.

Fluorescence Molecular Tomography: Principles and Potential for Pharmaceutical Research

PubMed Central

Stuker, Florian; Ripoll, Jorge; Rudin, Markus

2011-01-01

Fluorescence microscopic imaging is widely used in biomedical research to study molecular and cellular processes in cell culture or tissue samples. This is motivated by the high inherent sensitivity of fluorescence techniques, the spatial resolution that compares favorably with cellular dimensions, the stability of the fluorescent labels used and the sophisticated labeling strategies that have been developed for selectively labeling target molecules. More recently, two and three-dimensional optical imaging methods have also been applied to monitor biological processes in intact biological organisms such as animals or even humans. These whole body optical imaging approaches have to cope with the fact that biological tissue is a highly scattering and absorbing medium. As a consequence, light propagation in tissue is well described by a diffusion approximation and accurate reconstruction of spatial information is demanding. While in vivo optical imaging is a highly sensitive method, the signal is strongly surface weighted, i.e., the signal detected from the same light source will become weaker the deeper it is embedded in tissue, and strongly depends on the optical properties of the surrounding tissue. Derivation of quantitative information, therefore, requires tomographic techniques such as fluorescence molecular tomography (FMT), which maps the three-dimensional distribution of a fluorescent probe or protein concentration. The combination of FMT with a structural imaging method such as X-ray computed tomography (CT) or Magnetic Resonance Imaging (MRI) will allow mapping molecular information on a high definition anatomical reference and enable the use of prior information on tissue's optical properties to enhance both resolution and sensitivity. Today many of the fluorescent assays originally developed for studies in cellular systems have been successfully translated for experimental studies in animals. The opportunity of monitoring molecular processes non-invasively in the intact organism is highly attractive from a diagnostic point of view but even more so for the drug developer, who can use the techniques for proof-of-mechanism and proof-of-efficacy studies. This review shall elucidate the current status and potential of fluorescence tomography including recent advances in multimodality imaging approaches for preclinical and clinical drug development. PMID:24310495

Tomographic inversion techniques incorporating physical constraints for line integrated spectroscopy in stellarators and tokamaks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pablant, N. A.; Bell, R. E.; Bitter, M.

2014-11-15

Accurate tomographic inversion is important for diagnostic systems on stellarators and tokamaks which rely on measurements of line integrated emission spectra. A tomographic inversion technique based on spline optimization with enforcement of constraints is described that can produce unique and physically relevant inversions even in situations with noisy or incomplete input data. This inversion technique is routinely used in the analysis of data from the x-ray imaging crystal spectrometer (XICS) installed at the Large Helical Device. The XICS diagnostic records a 1D image of line integrated emission spectra from impurities in the plasma. Through the use of Doppler spectroscopy andmore » tomographic inversion, XICS can provide profile measurements of the local emissivity, temperature, and plasma flow. Tomographic inversion requires the assumption that these measured quantities are flux surface functions, and that a known plasma equilibrium reconstruction is available. In the case of low signal levels or partial spatial coverage of the plasma cross-section, standard inversion techniques utilizing matrix inversion and linear-regularization often cannot produce unique and physically relevant solutions. The addition of physical constraints, such as parameter ranges, derivative directions, and boundary conditions, allow for unique solutions to be reliably found. The constrained inversion technique described here utilizes a modified Levenberg-Marquardt optimization scheme, which introduces a condition avoidance mechanism by selective reduction of search directions. The constrained inversion technique also allows for the addition of more complicated parameter dependencies, for example, geometrical dependence of the emissivity due to asymmetries in the plasma density arising from fast rotation. The accuracy of this constrained inversion technique is discussed, with an emphasis on its applicability to systems with limited plasma coverage.« less

Computed Tomographic Blend Sign Is Associated With Computed Tomographic Angiography Spot Sign and Predicts Secondary Neurological Deterioration After Intracerebral Hemorrhage.

PubMed

Sporns, Peter B; Schwake, Michael; Schmidt, Rene; Kemmling, André; Minnerup, Jens; Schwindt, Wolfram; Cnyrim, Christian; Zoubi, Tarek; Heindel, Walter; Niederstadt, Thomas; Hanning, Uta

2017-01-01

Significant early hematoma growth in patients with intracerebral hemorrhage is an independent predictor of poor functional outcome. Recently, the novel blend sign (BS) has been introduced as a new imaging sign for predicting hematoma growth in noncontrast computed tomography. Another parameter predicting increasing hematoma size is the well-established spot sign (SS) visible in computed tomographic angiography. We, therefore, aimed to clarify the association between established SS and novel BS and their values predicting a secondary neurological deterioration. Retrospective study inclusion criteria were (1) spontaneous intracerebral hemorrhage confirmed on noncontrast computed tomography and (2) noncontrast computed tomography and computed tomographic angiography performed on admission within 6 hours after onset of symptoms. We defined a binary outcome (secondary neurological deterioration versus no secondary deterioration). As secondary neurological deterioration, we defined (1) early hemicraniectomy under standardized criteria or (2) secondary decrease of Glasgow Coma Scale of >3 points, both within the first 48 hours after symptom onset. Of 182 patients with spontaneous intracerebral hemorrhage, 37 (20.3%) presented with BS and 39 (21.4%) with SS. Of the 81 patients with secondary deterioration, 31 (38.3%) had BS and SS on admission. Multivariable logistic regression analysis identified hematoma volume (odds ratio, 1.07 per mL; P≤0.001), intraventricular hemorrhage (odds ratio, 3.08; P=0.008), and the presence of BS (odds ratio, 11.47; P≤0.001) as independent predictors of neurological deterioration. The BS, which is obtainable in noncontrast computed tomography, shows a high correlation with the computed tomographic angiography SS and is a reliable predictor of secondary neurological deterioration after spontaneous intracerebral hemorrhage. © 2016 American Heart Association, Inc.

Tomographic inversion techniques incorporating physical constraints for line integrated spectroscopy in stellarators and tokamaksa)

DOE PAGES

Pablant, N. A.; Bell, R. E.; Bitter, M.; ...

2014-08-08

Accurate tomographic inversion is important for diagnostic systems on stellarators and tokamaks which rely on measurements of line integrated emission spectra. A tomographic inversion technique based on spline optimization with enforcement of constraints is described that can produce unique and physically relevant inversions even in situations with noisy or incomplete input data. This inversion technique is routinely used in the analysis of data from the x-ray imaging crystal spectrometer (XICS) installed at LHD. The XICS diagnostic records a 1D image of line integrated emission spectra from impurities in the plasma. Through the use of Doppler spectroscopy and tomographic inversion, XICSmore » can provide pro file measurements of the local emissivity, temperature and plasma flow. Tomographic inversion requires the assumption that these measured quantities are flux surface functions, and that a known plasma equilibrium reconstruction is available. In the case of low signal levels or partial spatial coverage of the plasma cross-section, standard inversion techniques utilizing matrix inversion and linear-regularization often cannot produce unique and physically relevant solutions. The addition of physical constraints, such as parameter ranges, derivative directions, and boundary conditions, allow for unique solutions to be reliably found. The constrained inversion technique described here utilizes a modifi ed Levenberg-Marquardt optimization scheme, which introduces a condition avoidance mechanism by selective reduction of search directions. The constrained inversion technique also allows for the addition of more complicated parameter dependencies, for example geometrical dependence of the emissivity due to asymmetries in the plasma density arising from fast rotation. The accuracy of this constrained inversion technique is discussed, with an emphasis on its applicability to systems with limited plasma coverage.« less

Downscaling Smooth Tomographic Models: Separating Intrinsic and Apparent Anisotropy

NASA Astrophysics Data System (ADS)

Bodin, Thomas; Capdeville, Yann; Romanowicz, Barbara

2016-04-01

In recent years, a number of tomographic models based on full waveform inversion have been published. Due to computational constraints, the fitted waveforms are low pass filtered, which results in an inability to map features smaller than half the shortest wavelength. However, these tomographic images are not a simple spatial average of the true model, but rather an effective, apparent, or equivalent model that provides a similar 'long-wave' data fit. For example, it can be shown that a series of horizontal isotropic layers will be seen by a 'long wave' as a smooth anisotropic medium. In this way, the observed anisotropy in tomographic models is a combination of intrinsic anisotropy produced by lattice-preferred orientation (LPO) of minerals, and apparent anisotropy resulting from the incapacity of mapping discontinuities. Interpretations of observed anisotropy (e.g. in terms of mantle flow) requires therefore the separation of its intrinsic and apparent components. The "up-scaling" relations that link elastic properties of a rapidly varying medium to elastic properties of the effective medium as seen by long waves are strongly non-linear and their inverse highly non-unique. That is, a smooth homogenized effective model is equivalent to a large number of models with discontinuities. In the 1D case, Capdeville et al (GJI, 2013) recently showed that a tomographic model which results from the inversion of low pass filtered waveforms is an homogenized model, i.e. the same as the model computed by upscaling the true model. Here we propose a stochastic method to sample the ensemble of layered models equivalent to a given tomographic profile. We use a transdimensional formulation where the number of layers is variable. Furthermore, each layer may be either isotropic (1 parameter) or intrinsically anisotropic (2 parameters). The parsimonious character of the Bayesian inversion gives preference to models with the least number of parameters (i.e. least number of layers, and maximum number of isotropic layers). The non-uniqueness of the problem can be addressed by adding high frequency data such as receiver functions, able to map first order discontinuities. We show with synthetic tests that this method enables us to distinguish between intrinsic and apparent anisotropy in tomographic models, as layers with intrinsic anisotropy are only present when required by the data. A real data example is presented based on the latest global model produced at Berkeley.

Quantitative Whole Body Biodistribution of Fluorescent-Labeled Agents by Non-Invasive Tomographic Imaging

PubMed Central

Vasquez, Kristine O.; Casavant, Chelsea; Peterson, Jeffrey D.

2011-01-01

When small molecules or proteins are injected into live animals, their physical and chemical properties will significantly affect pharmacokinetics, tissue penetration, and the ultimate routes of metabolism and clearance. Fluorescence molecular tomography (FMT) offers the ability to non-invasively image and quantify temporal changes in fluorescence throughout the major organ systems of living animals, in a manner analogous to traditional approaches with radiolabeled agents. This approach is best used with biotherapeutics (therapeutic antibodies, or other large proteins) or large-scaffold drug-delivery vectors, that are minimally affected by low-level fluorophore conjugation. Application to small molecule drugs should take into account the significant impact of fluorophore labeling on size and physicochemical properties, however, the presents studies show that this technique is readily applied to small molecule agents developed for far-red (FR) or near infrared (NIR) imaging. Quantification by non-invasive FMT correlated well with both fluorescence from tissue homogenates as well as with planar (2D) fluorescence reflectance imaging of excised intact organs (r2 = 0.996 and 0.969, respectively). Dynamic FMT imaging (multiple times from 0 to 24 h) performed in live mice after the injection of four different FR/NIR-labeled agents, including immunoglobulin, 20–50 nm nanoparticles, a large vascular imaging agent, and a small molecule integrin antagonist, showed clear differences in the percentage of injected dose per gram of tissue (%ID/g) in liver, kidney, and bladder signal. Nanoparticles and IgG1 favored liver over kidney signal, the small molecule integrin-binding agent favored rapid kidney and bladder clearance, and the vascular agent, showed both liver and kidney clearance. Further assessment of the volume of distribution of these agents by fluorescent volume added information regarding their biodistribution and highlighted the relatively poor extravasation into tissue by IgG1. These studies demonstrate the ability of quantitative FMT imaging of FR/NIR agents to non-invasively visualize and quantify the biodistribution of different agents over time. PMID:21731618

Functional-Lesion Investigation of Developmental Stuttering with Positron Emission Tomography.

ERIC Educational Resources Information Center

Ingham, Roger J.; And Others

1996-01-01

Analysis of use of positron emission tomographic measurements of resting-state regional cerebral blood flow in 29 men, 10 of whom stuttered, did not support the idea that developmental stuttering is associated with abnormalities of blood flow at rest. Findings did suggest an essentially normal functional brain terrain with a small number of minor…

A new art code for tomographic interferometry

NASA Technical Reports Server (NTRS)

Tan, H.; Modarress, D.

1987-01-01

A new algebraic reconstruction technique (ART) code based on the iterative refinement method of least squares solution for tomographic reconstruction is presented. Accuracy and the convergence of the technique is evaluated through the application of numerically generated interferometric data. It was found that, in general, the accuracy of the results was superior to other reported techniques. The iterative method unconditionally converged to a solution for which the residual was minimum. The effects of increased data were studied. The inversion error was found to be a function of the input data error only. The convergence rate, on the other hand, was affected by all three parameters. Finally, the technique was applied to experimental data, and the results are reported.

Associations Between Collateral Status and Thrombus Characteristics and Their Impact in Anterior Circulation Stroke.

PubMed

Alves, Heitor C; Treurniet, Kilian M; Dutra, Bruna G; Jansen, Ivo G H; Boers, Anna M M; Santos, Emilie M M; Berkhemer, Olvert A; Dippel, Diederik W J; van der Lugt, Aad; van Zwam, Wim H; van Oostenbrugge, Robert J; Lingsma, Hester F; Roos, Yvo B W E M; Yoo, Albert J; Marquering, Henk A; Majoie, Charles B L M

2018-02-01

Thrombus characteristics and collateral score are associated with functional outcome in patients with acute ischemic stroke. It has been suggested that they affect each other. The aim of this study is to evaluate the association between clot burden score, thrombus perviousness, and collateral score and to determine whether collateral score influences the association of thrombus characteristics with functional outcome. Patients with baseline thin-slice noncontrast computed tomography and computed tomographic angiography images from the MR CLEAN trial (Multicenter Randomized Clinical Trial of Endovascular Treatment of Acute Ischemic Stroke in the Netherlands) were included (n=195). Collateral score and clot burden scores were determined on baseline computed tomographic angiography. Thrombus attenuation increase was determined by comparing thrombus density on noncontrast computed tomography and computed tomographic angiography using a semiautomated method. The association of collateral score with clot burden score and thrombus attenuation increase was evaluated with linear regression. Mediation and effect modification analyses were used to assess the influence of collateral score on the association of clot burden score and thrombus attenuation increase with functional outcome. A higher clot burden score (B=0.063; 95% confidence interval, 0.008-0.118) and a higher thrombus attenuation increase (B=0.014; 95% confidence interval, 0.003-0.026) were associated with higher collateral score. Collateral score mediated the association of clot burden score with functional outcome. The association between thrombus attenuation increase and functional outcome was modified by the collateral score, and this association was stronger in patients with moderate and good collaterals. Patients with lower thrombus burden and higher thrombus perviousness scores had higher collateral score. The positive effect of thrombus perviousness on clinical outcome was only present in patients with moderate and high collateral scores. URL: http://www.trialregister.nl. Unique identifier: NTR1804 and URL: http://www.controlled-trials.com Unique identifier: ISRCTN10888758. © 2018 The Authors.

Iterative Reconstruction of Volumetric Particle Distribution for 3D Velocimetry

NASA Astrophysics Data System (ADS)

Wieneke, Bernhard; Neal, Douglas

2011-11-01

A number of different volumetric flow measurement techniques exist for following the motion of illuminated particles. For experiments that have lower seeding densities, 3D-PTV uses recorded images from typically 3-4 cameras and then tracks the individual particles in space and time. This technique is effective in flows that have lower seeding densities. For flows that have a higher seeding density, tomographic PIV uses a tomographic reconstruction algorithm (e.g. MART) to reconstruct voxel intensities of the recorded volume followed by the cross-correlation of subvolumes to provide the instantaneous 3D vector fields on a regular grid. A new hybrid algorithm is presented which iteratively reconstructs the 3D-particle distribution directly using particles with certain imaging properties instead of voxels as base functions. It is shown with synthetic data that this method is capable of reconstructing densely seeded flows up to 0.05 particles per pixel (ppp) with the same or higher accuracy than 3D-PTV and tomographic PIV. Finally, this new method is validated using experimental data on a turbulent jet.

Three-dimensional computed tomographic volumetry precisely predicts the postoperative pulmonary function.

PubMed

Kobayashi, Keisuke; Saeki, Yusuke; Kitazawa, Shinsuke; Kobayashi, Naohiro; Kikuchi, Shinji; Goto, Yukinobu; Sakai, Mitsuaki; Sato, Yukio

2017-11-01

It is important to accurately predict the patient's postoperative pulmonary function. The aim of this study was to compare the accuracy of predictions of the postoperative residual pulmonary function obtained with three-dimensional computed tomographic (3D-CT) volumetry with that of predictions obtained with the conventional segment-counting method. Fifty-three patients scheduled to undergo lung cancer resection, pulmonary function tests, and computed tomography were enrolled in this study. The postoperative residual pulmonary function was predicted based on the segment-counting and 3D-CT volumetry methods. The predicted postoperative values were compared with the results of postoperative pulmonary function tests. Regarding the linear correlation coefficients between the predicted postoperative values and the measured values, those obtained using the 3D-CT volumetry method tended to be higher than those acquired using the segment-counting method. In addition, the variations between the predicted and measured values were smaller with the 3D-CT volumetry method than with the segment-counting method. These results were more obvious in COPD patients than in non-COPD patients. Our findings suggested that the 3D-CT volumetry was able to predict the residual pulmonary function more accurately than the segment-counting method, especially in patients with COPD. This method might lead to the selection of appropriate candidates for surgery among patients with a marginal pulmonary function.

Dense velocity reconstruction from tomographic PTV with material derivatives

NASA Astrophysics Data System (ADS)

Schneiders, Jan F. G.; Scarano, Fulvio

2016-09-01

A method is proposed to reconstruct the instantaneous velocity field from time-resolved volumetric particle tracking velocimetry (PTV, e.g., 3D-PTV, tomographic PTV and Shake-the-Box), employing both the instantaneous velocity and the velocity material derivative of the sparse tracer particles. The constraint to the measured temporal derivative of the PTV particle tracks improves the consistency of the reconstructed velocity field. The method is christened as pouring time into space, as it leverages temporal information to increase the spatial resolution of volumetric PTV measurements. This approach becomes relevant in cases where the spatial resolution is limited by the seeding concentration. The method solves an optimization problem to find the vorticity and velocity fields that minimize a cost function, which includes next to instantaneous velocity, also the velocity material derivative. The velocity and its material derivative are related through the vorticity transport equation, and the cost function is minimized using the limited-memory Broyden-Fletcher-Goldfarb-Shanno (L-BFGS) algorithm. The procedure is assessed numerically with a simulated PTV experiment in a turbulent boundary layer from a direct numerical simulation (DNS). The experimental validation considers a tomographic particle image velocimetry (PIV) experiment in a similar turbulent boundary layer and the additional case of a jet flow. The proposed technique (`vortex-in-cell plus', VIC+) is compared to tomographic PIV analysis (3D iterative cross-correlation), PTV interpolation methods (linear and adaptive Gaussian windowing) and to vortex-in-cell (VIC) interpolation without the material derivative. A visible increase in resolved details in the turbulent structures is obtained with the VIC+ approach, both in numerical simulations and experiments. This results in a more accurate determination of the turbulent stresses distribution in turbulent boundary layer investigations. Data from a jet experiment, where the vortex topology is retrieved with a small number of tracers indicate the potential utilization of VIC+ in low-concentration experiments as for instance occurring in large-scale volumetric PTV measurements.

Limited-angle tomography for analyzer-based phase-contrast X-ray imaging

PubMed Central

Majidi, Keivan; Wernick, Miles N; Li, Jun; Muehleman, Carol; Brankov, Jovan G

2014-01-01

Multiple-Image Radiography (MIR) is an analyzer-based phase-contrast X-ray imaging method (ABI), which is emerging as a potential alternative to conventional radiography. MIR simultaneously generates three planar parametric images containing information about scattering, refraction and attenuation properties of the object. The MIR planar images are linear tomographic projections of the corresponding object properties, which allows reconstruction of volumetric images using computed tomography (CT) methods. However, when acquiring a full range of linear projections around the tissue of interest is not feasible or the scanning time is limited, limited-angle tomography techniques can be used to reconstruct these volumetric images near the central plane, which is the plane that contains the pivot point of the tomographic movement. In this work, we use computer simulations to explore the applicability of limited-angle tomography to MIR. We also investigate the accuracy of reconstructions as a function of number of tomographic angles for a fixed total radiation exposure. We use this function to find an optimal range of angles over which data should be acquired for limited-angle tomography MIR (LAT-MIR). Next, we apply the LAT-MIR technique to experimentally acquired MIR projections obtained in a cadaveric human thumb study. We compare the reconstructed slices near the central plane to the same slices reconstructed by CT-MIR using the full angular view around the object. Finally, we perform a task-based evaluation of LAT-MIR performance for different numbers of angular views, and use template matching to detect cartilage in the refraction image near the central plane. We use the signal-to-noise ratio of this test as the detectability metric to investigate an optimum range of tomographic angles for detecting soft tissues in LAT-MIR. Both results show that there is an optimum range of angular view for data acquisition where LAT-MIR yields the best performance, comparable to CT-MIR only if one considers volumetric images near the central plane and not the whole volume. PMID:24898008

Limited-angle tomography for analyzer-based phase-contrast x-ray imaging

NASA Astrophysics Data System (ADS)

Majidi, Keivan; Wernick, Miles N.; Li, Jun; Muehleman, Carol; Brankov, Jovan G.

2014-07-01

Multiple-image radiography (MIR) is an analyzer-based phase-contrast x-ray imaging method, which is emerging as a potential alternative to conventional radiography. MIR simultaneously generates three planar parametric images containing information about scattering, refraction and attenuation properties of the object. The MIR planar images are linear tomographic projections of the corresponding object properties, which allows reconstruction of volumetric images using computed tomography (CT) methods. However, when acquiring a full range of linear projections around the tissue of interest is not feasible or the scanning time is limited, limited-angle tomography techniques can be used to reconstruct these volumetric images near the central plane, which is the plane that contains the pivot point of the tomographic movement. In this work, we use computer simulations to explore the applicability of limited-angle tomography to MIR. We also investigate the accuracy of reconstructions as a function of number of tomographic angles for a fixed total radiation exposure. We use this function to find an optimal range of angles over which data should be acquired for limited-angle tomography MIR (LAT-MIR). Next, we apply the LAT-MIR technique to experimentally acquired MIR projections obtained in a cadaveric human thumb study. We compare the reconstructed slices near the central plane to the same slices reconstructed by CT-MIR using the full angular view around the object. Finally, we perform a task-based evaluation of LAT-MIR performance for different numbers of angular views, and use template matching to detect cartilage in the refraction image near the central plane. We use the signal-to-noise ratio of this test as the detectability metric to investigate an optimum range of tomographic angles for detecting soft tissues in LAT-MIR. Both results show that there is an optimum range of angular view for data acquisition where LAT-MIR yields the best performance, comparable to CT-MIR only if one considers volumetric images near the central plane and not the whole volume.

In vivo quantitative imaging of point-like bioluminescent and fluorescent sources: Validation studies in phantoms and small animals post mortem

NASA Astrophysics Data System (ADS)

Comsa, Daria Craita

2008-10-01

There is a real need for improved small animal imaging techniques to enhance the development of therapies in which animal models of disease are used. Optical methods for imaging have been extensively studied in recent years, due to their high sensitivity and specificity. Methods like bioluminescence and fluorescence tomography report promising results for 3D reconstructions of source distributions in vivo. However, no standard methodology exists for optical tomography, and various groups are pursuing different approaches. In a number of studies on small animals, the bioluminescent or fluorescent sources can be reasonably approximated as point or line sources. Examples include images of bone metastases confined to the bone marrow. Starting with this premise, we propose a simpler, faster, and inexpensive technique to quantify optical images of point-like sources. The technique avoids the computational burden of a tomographic method by using planar images and a mathematical model based on diffusion theory. The model employs in situ optical properties estimated from video reflectometry measurements. Modeled and measured images are compared iteratively using a Levenberg-Marquardt algorithm to improve estimates of the depth and strength of the bioluminescent or fluorescent inclusion. The performance of the technique to quantify bioluminescence images was first evaluated on Monte Carlo simulated data. Simulated data also facilitated a methodical investigation of the effect of errors in tissue optical properties on the retrieved source depth and strength. It was found that, for example, an error of 4 % in the effective attenuation coefficient led to 4 % error in the retrieved depth for source depths of up to 12mm, while the error in the retrieved source strength increased from 5.5 % at 2mm depth, to 18 % at 12mm depth. Experiments conducted on images from homogeneous tissue-simulating phantoms showed that depths up to 10mm could be estimated within 8 %, and the relative source strength within 20 %. For sources 14mm deep, the inaccuracy in determining the relative source strength increased to 30 %. Measurements on small animals post mortem showed that the use of measured in situ optical properties to characterize heterogeneous tissue resulted in a superior estimation of the source strength and depth compared to when literature optical properties for organs or tissues were used. Moreover, it was found that regardless of the heterogeneity of the implant location or depth, our algorithm consistently showed an advantage over the simple assessment of the source strength based on the signal strength in the emission image. Our bioluminescence algorithm was generally able to predict the source strength within a factor of 2 of the true strength, but the performance varied with the implant location and depth. In fluorescence imaging a more complex technique is required, including knowledge of tissue optical properties at both the excitation and emission wavelengths. A theoretical study using simulated fluorescence data showed that, for example, for a source 5 mm deep in tissue, errors of up to 15 % in the optical properties would give rise to errors of +/-0.7 mm in the retrieved depth and the source strength would be over- or under-estimated by a factor ranging from 1.25 to 2. Fluorescent sources implanted in rats post mortem at the same depth were localized with an error just slightly higher than predicted theoretically: a root-mean-square value of 0.8 mm was obtained for all implants 5 mm deep. However, for this source depth, the source strength was assessed within a factor ranging from 1.3 to 4.2 from the value estimated in a controlled medium. Nonetheless, similarly to the bioluminescence study, the fluorescence quantification algorithm consistently showed an advantage over the simple assessment of the source strength based on the signal strength in the fluorescence image. Few studies have been reported in the literature that reconstruct known sources of bioluminescence or fluorescence in vivo or in heterogeneous phantoms. The few reported results show that the 3D tomographic methods have not yet reached their full potential. In this context, the simplicity of our technique emerges as a strong advantage.

Multi-modal molecular diffuse optical tomography system for small animal imaging

PubMed Central

Guggenheim, James A.; Basevi, Hector R. A.; Frampton, Jon; Styles, Iain B.; Dehghani, Hamid

2013-01-01

A multi-modal optical imaging system for quantitative 3D bioluminescence and functional diffuse imaging is presented, which has no moving parts and uses mirrors to provide multi-view tomographic data for image reconstruction. It is demonstrated that through the use of trans-illuminated spectral near infrared measurements and spectrally constrained tomographic reconstruction, recovered concentrations of absorbing agents can be used as prior knowledge for bioluminescence imaging within the visible spectrum. Additionally, the first use of a recently developed multi-view optical surface capture technique is shown and its application to model-based image reconstruction and free-space light modelling is demonstrated. The benefits of model-based tomographic image recovery as compared to 2D planar imaging are highlighted in a number of scenarios where the internal luminescence source is not visible or is confounding in 2D images. The results presented show that the luminescence tomographic imaging method produces 3D reconstructions of individual light sources within a mouse-sized solid phantom that are accurately localised to within 1.5mm for a range of target locations and depths indicating sensitivity and accurate imaging throughout the phantom volume. Additionally the total reconstructed luminescence source intensity is consistent to within 15% which is a dramatic improvement upon standard bioluminescence imaging. Finally, results from a heterogeneous phantom with an absorbing anomaly are presented demonstrating the use and benefits of a multi-view, spectrally constrained coupled imaging system that provides accurate 3D luminescence images. PMID:24954977

Computerized tomographic quantification of chronic obstructive pulmonary disease as the principal determinant of frontal P vector.

PubMed

Chhabra, Lovely; Sareen, Pooja; Gandagule, Amit; Spodick, David

2012-04-01

Verticalization of the P-wave axis is characteristic of chronic obstructive pulmonary disease (COPD). We studied the correlation of P-wave axis and computerized tomographically quantified emphysema in patients with COPD/emphysema. Individual correlation of P-wave axis with different structural types of emphysema was also studied. High-resolution computerized tomographic scans of 23 patients >45 years old with known COPD were reviewed to assess the type and extent of emphysema using computerized tomographic densitometric parameters. Electrocardiograms were then independently reviewed and the P-wave axis was calculated in customary fashion. Degree of the P vector (DOPV) and radiographic percent emphysematous area (RPEA) were compared for statistical correlation. The P vector and RPEA were also directly compared to the forced expiratory volume at 1 second. RPEA and the P vector had a significant positive correlation in all patients (r = +0.77, p <0.0001) but correlation was very strong in patients with predominant lower lobe emphysema (r = +0.89, p <0.001). Forced expiratory volume at 1 second and the P vector had almost a linear inverse correlation in predominantly lower lobe emphysema (r = -0.92, p <0.001). DOPV positively correlated with radiographically quantified emphysema. DOPV and RPEA were strong predictors of qualitative lung function in patients with predominantly lower lobe emphysema. In conclusion, a combination of high DOPV and predominantly lower lobe emphysema indicates severe obstructive lung dysfunction in patients with COPD. Copyright © 2012 Elsevier Inc. All rights reserved.

Intra-LLSVP Heterogeneity from Spherical Slepian Analysis

NASA Astrophysics Data System (ADS)

Olugboji, T. M.; Moulik, P.; Plattner, A.; Lekic, V.

2017-12-01

The lower mantle structure is dominated by a pair of large, antipodal, low shear velocity provinces (LLSVPs) located beneath Africa and the Pacific Ocean. Though LLSVPs are a dominantly long-wavelength (degree 2) feature detected since the earliest tomographic models, their nature and origin remain enigmatic. A number of hypotheses have been proposed to address their origin, summarized by two end member scenarios: (1) they represent thermochemical piles that are either primordial or have grown over time, such as by the accumulation of subducted oceanic lithosphere, (2) they are purely thermal features, seen through the lens of tomographic imaging. In order to distinguish between these two interpretations of the seismically detected LLSVPs we compare the amplitude and length-scales of velocity heterogeneities within and outside the LLSVPs, and analyze their variation with height above the core-mantle boundary. This requires estimating the wavenumber spectrum of heterogeneity by localizing it from a global tomographic model. Previous researchers have done this by filtering using spatially abrupt windowing functions; however, this procedure leads to unreliable spectral estimates due to their non-compact spatiospectral concentration. Here, we overcome this shortcoming by adopting spherical Slepian analysis that allows us to optimize the trade-off between spatial localization and spectral leakage. We conduct a quantitative analysis of the similarities and differences in the spectrum of heterogeneity across a collection of global tomographic models allowing us to identify robust features that need to be explained by purely thermal or thermochemical geodynamic models, potentially discriminating between these two scenarios.

Crustal Structure Beneath Taiwan Using Frequency-band Inversion of Receiver Function Waveforms

NASA Astrophysics Data System (ADS)

Tomfohrde, D. A.; Nowack, R. L.

Receiver function analysis is used to determine local crustal structure beneath Taiwan. We have performed preliminary data processing and polarization analysis for the selection of stations and events and to increase overall data quality. Receiver function analysis is then applied to data from the Taiwan Seismic Network to obtain radial and transverse receiver functions. Due to the limited azimuthal coverage, only the radial receiver functions are analyzed in terms of horizontally layered crustal structure for each station. In order to improve convergence of the receiver function inversion, frequency-band inversion (FBI) is implemented, in which an iterative inversion procedure with sequentially higher low-pass corner frequencies is used to stabilize the waveform inversion. Frequency-band inversion is applied to receiver functions at six stations of the Taiwan Seismic Network. Initial 20-layer crustal models are inverted for using prior tomographic results for the initial models. The resulting 20-1ayer models are then simplified to 4 to 5 layer models and input into an alternating depth and velocity frequency-band inversion. For the six stations investigated, the resulting simplified models provide an average estimate of 38 km for the Moho thickness surrounding the Central Range of Taiwan. Also, the individual station estimates compare well with the recent tomographic model of and the refraction results of Rau and Wu (1995) and the refraction results of Ma and Song (1997).

Fractional Flow Reserve and Coronary Computed Tomographic Angiography: A Review and Critical Analysis.

PubMed

Hecht, Harvey S; Narula, Jagat; Fearon, William F

2016-07-08

Invasive fractional flow reserve (FFR) is now the gold standard for intervention. Noninvasive functional imaging analyses derived from coronary computed tomographic angiography (CTA) offer alternatives for evaluating lesion-specific ischemia. CT-FFR, CT myocardial perfusion imaging, and transluminal attenuation gradient/corrected contrast opacification have been studied using invasive FFR as the gold standard. CT-FFR has demonstrated significant improvement in specificity and positive predictive value compared with CTA alone for predicting FFR of ≤0.80, as well as decreasing the frequency of nonobstructive invasive coronary angiography. High-risk plaque characteristics have also been strongly implicated in abnormal FFR. Myocardial computed tomographic perfusion is an alternative method with promising results; it involves more radiation and contrast. Transluminal attenuation gradient/corrected contrast opacification is more controversial and may be more related to vessel diameter than stenosis. Important considerations remain: (1) improvement of CTA quality to decrease unevaluable studies, (2) is the diagnostic accuracy of CT-FFR sufficient? (3) can CT-FFR guide intervention without invasive FFR confirmation? (4) what are the long-term outcomes of CT-FFR-guided treatment and how do they compare with other functional imaging-guided paradigms? (5) what degree of stenosis on CTA warrants CT-FFR? (6) how should high-risk plaque be incorporated into treatment decisions? (7) how will CT-FFR influence other functional imaging test utilization, and what will be the effect on the practice of cardiology? (8) will a workstation-based CT-FFR be mandatory? Rapid progress to date suggests that CTA-based lesion-specific ischemia will be the gatekeeper to the cardiac catheterization laboratory and will transform the world of intervention. © 2016 American Heart Association, Inc.

Electrotonic coupling of excitable and nonexcitable cells in the heart revealed by optogenetics

PubMed Central

Quinn, T. Alexander; Camelliti, Patrizia; Rog-Zielinska, Eva A.; Siedlecka, Urszula; Poggioli, Tommaso; O'Toole, Eileen T.; Knöpfel, Thomas; Kohl, Peter

2016-01-01

Electrophysiological studies of excitable organs usually focus on action potential (AP)-generating cells, whereas nonexcitable cells are generally considered as barriers to electrical conduction. Whether nonexcitable cells may modulate excitable cell function or even contribute to AP conduction via direct electrotonic coupling to AP-generating cells is unresolved in the heart: such coupling is present in vitro, but conclusive evidence in situ is lacking. We used genetically encoded voltage-sensitive fluorescent protein 2.3 (VSFP2.3) to monitor transmembrane potential in either myocytes or nonmyocytes of murine hearts. We confirm that VSFP2.3 allows measurement of cell type-specific electrical activity. We show that VSFP2.3, expressed solely in nonmyocytes, can report cardiomyocyte AP-like signals at the border of healed cryoinjuries. Using EM-based tomographic reconstruction, we further discovered tunneling nanotube connections between myocytes and nonmyocytes in cardiac scar border tissue. Our results provide direct electrophysiological evidence of heterocellular electrotonic coupling in native myocardium and identify tunneling nanotubes as a possible substrate for electrical cell coupling that may be in addition to previously discovered connexins at sites of myocyte–nonmyocyte contact in the heart. These findings call for reevaluation of cardiac nonmyocyte roles in electrical connectivity of the heterocellular heart. PMID:27930302

Tomographic three-dimensional echocardiographic determination of chamber size and systolic function in patients with left ventricular aneurysm: comparison to magnetic resonance imaging, cineventriculography, and two-dimensional echocardiography.

PubMed

Buck, T; Hunold, P; Wentz, K U; Tkalec, W; Nesser, H J; Erbel, R

1997-12-16

Two-dimensional (2D) echocardiographic approaches based on geometric assumptions face the greatest limitations and inaccuracies in patients with left ventricular (LV) aneurysms. Three-dimensional (3D) echocardiographic techniques can potentially overcome these limitations; to date, however, although tested in experimental models of aneurysms, they have not been applied to a series of patients with such distortion. The purpose of this study was therefore to validate the clinical application of tomographic 3D echocardiography (3DE) by the routine transthoracic approach to determine LV chamber size and systolic function without geometric assumptions in patients with LV aneurysms. In 23 patients with chronic stable LV aneurysms, LV end-systolic and end-diastolic volumes (LVEDV, LVESV) and ejection fraction (LVEF) by tomographic 3DE were compared with results from 3D magnetic resonance tomography (3DMRT) as an independent reference as well as with the conventional techniques of single plane and biplane 2D echocardiography and biplane cineventriculography. Dynamic 3DE image data sets were obtained from a transthoracic apical view with the use of a rotating probe with acquisition gated to control for ECG and respiration (Echoscan, TomTec). Volumes were calculated from the 3D data sets by summating the volumes of multiple parallel disks. 3DE results correlated and agreed well with those by 3DMRT, with better correlation and agreement than provided by other techniques for LVEDV (3DE: r=.97, SEE=14.7 mL, SD of differences from 3DMRT=14.5 mL; other techniques: r=.84 to .93, SEE=30.7 to 41.6 mL [P<.001 versus 3DE by F test], SD of differences=31.5 to 40.7 mL [P<.001 versus 3DE by F test]). The same also pertained to LVESV (3DE: r=.97, SEE=12.4 mL, SD of differences=12.9 mL; other techniques: r=.81 to .90, SEE=24.7 to 37.2 mL [P<.001], SD of differences=27.6 to 36.8 mL [P<.005]) and LVEF (3DE: r=.74, SEE=5.6%, SD of differences=6.7%; other techniques: r=.14 to .59, SEE=9.5% to 10.1% [P<.01], SD of differences=9.5% to 12.6% [P<.05]). Compared with 3DMRT, 3DE was less time consuming and patient discomfort was less. Tomographic 3DE is an accurate noninvasive technique for calculating LV volumes and systolic function in patients with LV aneurysm. Unlike current 2D methods, tomographic 3DE requires no geometric assumptions that limit accuracy.

Multiphoton tomography to detect chemo- and biohazards

NASA Astrophysics Data System (ADS)

König, Karsten

2015-03-01

In vivo high-resolution multiphoton/CARS tomography provides optical biopsies with 300 nm lateral resolution with chemical fingerprints. Thousands of volunteers and patients have been investigated for early cancer diagnosis, evaluation of anti-ageing cosmetic products, and changes of cellular metabolism by UV exposure and decreased oxygen supply. The skin as the outermost and largest organ is also the major target of CB agents. Current UV-based sensors are useful for bio-aerosol sensing but not for evaluating exposed in vivo skin. Here we evaluate the use of 4D multiphoton/CARS tomographs based on near infrared femtosecond laser radiation, time-correlated single photon counting (FLIM) and white light generation by photonic crystal fibers to detect bio- and chemohazards in human in vivo skin using twophoton fluorescence, SHG, and Raman signals.

Intensity-enhanced MART for tomographic PIV

NASA Astrophysics Data System (ADS)

Wang, HongPing; Gao, Qi; Wei, RunJie; Wang, JinJun

2016-05-01

A novel technique to shrink the elongated particles and suppress the ghost particles in particle reconstruction of tomographic particle image velocimetry is presented. This method, named as intensity-enhanced multiplicative algebraic reconstruction technique (IntE-MART), utilizes an inverse diffusion function and an intensity suppressing factor to improve the quality of particle reconstruction and consequently the precision of velocimetry. A numerical assessment about vortex ring motion with and without image noise is performed to evaluate the new algorithm in terms of reconstruction, particle elongation and velocimetry. The simulation is performed at seven different seeding densities. The comparison of spatial filter MART and IntE-MART on the probability density function of particle peak intensity suggests that one of the local minima of the distribution can be used to separate the ghosts and actual particles. Thus, ghost removal based on IntE-MART is also introduced. To verify the application of IntE-MART, a real plate turbulent boundary layer experiment is performed. The result indicates that ghost reduction can increase the accuracy of RMS of velocity field.

Diagnostic imaging advances in murine models of colitis.

PubMed

Brückner, Markus; Lenz, Philipp; Mücke, Marcus M; Gohar, Faekah; Willeke, Peter; Domagk, Dirk; Bettenworth, Dominik

2016-01-21

Inflammatory bowel diseases (IBD) such as Crohn's disease and ulcerative colitis are chronic-remittent inflammatory disorders of the gastrointestinal tract still evoking challenging clinical diagnostic and therapeutic situations. Murine models of experimental colitis are a vital component of research into human IBD concerning questions of its complex pathogenesis or the evaluation of potential new drugs. To monitor the course of colitis, to the present day, classical parameters like histological tissue alterations or analysis of mucosal cytokine/chemokine expression often require euthanasia of animals. Recent advances mean revolutionary non-invasive imaging techniques for in vivo murine colitis diagnostics are increasingly available. These novel and emerging imaging techniques not only allow direct visualization of intestinal inflammation, but also enable molecular imaging and targeting of specific alterations of the inflamed murine mucosa. For the first time, in vivo imaging techniques allow for longitudinal examinations and evaluation of intra-individual therapeutic response. This review discusses the latest developments in the different fields of ultrasound, molecularly targeted contrast agent ultrasound, fluorescence endoscopy, confocal laser endomicroscopy as well as tomographic imaging with magnetic resonance imaging, computed tomography and fluorescence-mediated tomography, discussing their individual limitations and potential future diagnostic applications in the management of human patients with IBD.

Kilohertz VLIF (volumetric laser induced fluorescence) measurements in a seeded free gas-phase jet in the transitionally turbulent flow regime

NASA Astrophysics Data System (ADS)

Wu, Yue; Xu, Wenjiang; Ma, Lin

2018-03-01

This paper reports the demonstration of instantaneous three-dimension (3D) measurements in turbulent flows at repetition rates up to 10 kHz using VLIF (volumetric laser induced fluorescence). The measurements were performed based on the LIF signal of iodine (I2) vapor seeded in the flow. The LIF signals of I2 vapor were generated volumetrically by a thick laser slab and then simultaneously captured by a total of seven cameras from different perspectives, based on which a 3D tomographic reconstruction was performed to obtain the 3D distribution of I2 vapor concentration. Single-shot measurements obtained in a duration of hundreds of nanoseconds (limited by the pulse duration of the excitation laser) were demonstrated in a 50 × 50 × 50 mm3 at a repetition rate up to 10 kHz. These measurements demonstrated the feasibility and potential of VLIF for resolving the 4D spatiotemporal dynamics of turbulent flows. Based on the experimental results obtained, this work also studied the VLIF signal level and its effects on the reconstruction accuracy under different the measurement conditions, illustrating the capabilities and limitations of performing high speed VLIF measurements.

Cryo X-ray microscope with flat sample geometry for correlative fluorescence and nanoscale tomographic imaging.

PubMed

Schneider, Gerd; Guttmann, Peter; Rehbein, Stefan; Werner, Stephan; Follath, Rolf

2012-02-01

X-ray imaging offers a new 3-D view into cells. With its ability to penetrate whole hydrated cells it is ideally suited for pairing fluorescence light microscopy and nanoscale X-ray tomography. In this paper, we describe the X-ray optical set-up and the design of the cryo full-field transmission X-ray microscope (TXM) at the electron storage ring BESSY II. Compared to previous TXM set-ups with zone plate condenser monochromator, the new X-ray optical layout employs an undulator source, a spherical grating monochromator and an elliptically shaped glass capillary mirror as condenser. This set-up improves the spectral resolution by an order of magnitude. Furthermore, the partially coherent object illumination improves the contrast transfer of the microscope compared to incoherent conditions. With the new TXM, cells grown on flat support grids can be tilted perpendicular to the optical axis without any geometrical restrictions by the previously required pinhole for the zone plate monochromator close to the sample plane. We also developed an incorporated fluorescence light microscope which permits to record fluorescence, bright field and DIC images of cryogenic cells inside the TXM. For TXM tomography, imaging with multi-keV X-rays is a straightforward approach to increase the depth of focus. Under these conditions phase contrast imaging is necessary. For soft X-rays with shrinking depth of focus towards 10nm spatial resolution, thin optical sections through a thick specimen might be obtained by deconvolution X-ray microscopy. As alternative 3-D X-ray imaging techniques, the confocal cryo-STXM and the dual beam cryo-FIB/STXM with photoelectron detection are proposed. Copyright © 2012 Elsevier Inc. All rights reserved.

Tomographic diagnostics of nonthermal plasmas

NASA Astrophysics Data System (ADS)

Denisova, Natalia

2009-10-01

In the previous work [1], we discussed a ``technology'' of tomographic method and relations between the tomographic diagnostics in thermal (equilibrium) and nonthermal (nonequilibrium) plasma sources. The conclusion has been made that tomographic reconstruction in thermal plasma sources is the standard procedure at present, which can provide much useful information on the plasma structure and its evolution in time, while the tomographic reconstruction of nonthermal plasma has a great potential at making a contribution to understanding the fundamental problem of substance behavior in strongly nonequilibrium conditions. Using medical terminology, one could say, that tomographic diagnostics of the equilibrium plasma sources studies their ``anatomic'' structure, while reconstruction of the nonequilibrium plasma is similar to the ``physiological'' examination: it is directed to study the physical mechanisms and processes. The present work is focused on nonthermal plasma research. The tomographic diagnostics is directed to study spatial structures formed in the gas discharge plasmas under the influence of electrical and gravitational fields. The ways of plasma ``self-organization'' in changing and extreme conditions are analyzed. The analysis has been made using some examples from our practical tomographic diagnostics of nonthermal plasma sources, such as low-pressure capacitive and inductive discharges. [0pt] [1] Denisova N. Plasma diagnostics using computed tomography method // IEEE Trans. Plasma Sci. 2009 37 4 502.

Arterial Obstruction on Computed Tomographic or Magnetic Resonance Angiography and Response to Intravenous Thrombolytics in Ischemic Stroke

PubMed Central

Mair, Grant; von Kummer, Rüdiger; Adami, Alessandro; White, Philip M.; Adams, Matthew E.; Yan, Bernard; Demchuk, Andrew M.; Farrall, Andrew J.; Sellar, Robin J.; Sakka, Eleni; Palmer, Jeb; Perry, David; Lindley, Richard I.; Sandercock, Peter A.G.

2017-01-01

Background and Purpose— Computed tomographic angiography and magnetic resonance angiography are used increasingly to assess arterial patency in patients with ischemic stroke. We determined which baseline angiography features predict response to intravenous thrombolytics in ischemic stroke using randomized controlled trial data. Methods— We analyzed angiograms from the IST-3 (Third International Stroke Trial), an international, multicenter, prospective, randomized controlled trial of intravenous alteplase. Readers, masked to clinical, treatment, and outcome data, assessed prerandomization computed tomographic angiography and magnetic resonance angiography for presence, extent, location, and completeness of obstruction and collaterals. We compared angiography findings to 6-month functional outcome (Oxford Handicap Scale) and tested for interactions with alteplase, using ordinal regression in adjusted analyses. We also meta-analyzed all available angiography data from other randomized controlled trials of intravenous thrombolytics. Results— In IST-3, 300 patients had prerandomization angiography (computed tomographic angiography=271 and magnetic resonance angiography=29). On multivariable analysis, more extensive angiographic obstruction and poor collaterals independently predicted poor outcome (P<0.01). We identified no significant interaction between angiography findings and alteplase effect on Oxford Handicap Scale (P≥0.075) in IST-3. In meta-analysis (5 trials of alteplase or desmoteplase, including IST-3, n=591), there was a significantly increased benefit of thrombolytics on outcome (odds ratio>1 indicates benefit) in patients with (odds ratio, 2.07; 95% confidence interval, 1.18–3.64; P=0.011) versus without (odds ratio, 0.88; 95% confidence interval, 0.58–1.35; P=0.566) arterial obstruction (P for interaction 0.017). Conclusions— Intravenous thrombolytics provide benefit to stroke patients with computed tomographic angiography or magnetic resonance angiography evidence of arterial obstruction, but the sample was underpowered to demonstrate significant treatment benefit or harm among patients with apparently patent arteries. Clinical Trial Registration— URL: http://www.isrctn.com. Unique identifier: ISRCTN25765518. PMID:28008093

Arterial Obstruction on Computed Tomographic or Magnetic Resonance Angiography and Response to Intravenous Thrombolytics in Ischemic Stroke.

PubMed

Mair, Grant; von Kummer, Rüdiger; Adami, Alessandro; White, Philip M; Adams, Matthew E; Yan, Bernard; Demchuk, Andrew M; Farrall, Andrew J; Sellar, Robin J; Sakka, Eleni; Palmer, Jeb; Perry, David; Lindley, Richard I; Sandercock, Peter A G; Wardlaw, Joanna M

2017-02-01

Computed tomographic angiography and magnetic resonance angiography are used increasingly to assess arterial patency in patients with ischemic stroke. We determined which baseline angiography features predict response to intravenous thrombolytics in ischemic stroke using randomized controlled trial data. We analyzed angiograms from the IST-3 (Third International Stroke Trial), an international, multicenter, prospective, randomized controlled trial of intravenous alteplase. Readers, masked to clinical, treatment, and outcome data, assessed prerandomization computed tomographic angiography and magnetic resonance angiography for presence, extent, location, and completeness of obstruction and collaterals. We compared angiography findings to 6-month functional outcome (Oxford Handicap Scale) and tested for interactions with alteplase, using ordinal regression in adjusted analyses. We also meta-analyzed all available angiography data from other randomized controlled trials of intravenous thrombolytics. In IST-3, 300 patients had prerandomization angiography (computed tomographic angiography=271 and magnetic resonance angiography=29). On multivariable analysis, more extensive angiographic obstruction and poor collaterals independently predicted poor outcome (P<0.01). We identified no significant interaction between angiography findings and alteplase effect on Oxford Handicap Scale (P≥0.075) in IST-3. In meta-analysis (5 trials of alteplase or desmoteplase, including IST-3, n=591), there was a significantly increased benefit of thrombolytics on outcome (odds ratio>1 indicates benefit) in patients with (odds ratio, 2.07; 95% confidence interval, 1.18-3.64; P=0.011) versus without (odds ratio, 0.88; 95% confidence interval, 0.58-1.35; P=0.566) arterial obstruction (P for interaction 0.017). Intravenous thrombolytics provide benefit to stroke patients with computed tomographic angiography or magnetic resonance angiography evidence of arterial obstruction, but the sample was underpowered to demonstrate significant treatment benefit or harm among patients with apparently patent arteries. URL: http://www.isrctn.com. Unique identifier: ISRCTN25765518. © 2016 The Authors.

Wave Propagation in Non-Stationary Statistical Mantle Models at the Global Scale

NASA Astrophysics Data System (ADS)

Meschede, M.; Romanowicz, B. A.

2014-12-01

We study the effect of statistically distributed heterogeneities that are smaller than the resolution of current tomographic models on seismic waves that propagate through the Earth's mantle at teleseismic distances. Current global tomographic models are missing small-scale structure as evidenced by the failure of even accurate numerical synthetics to explain enhanced coda in observed body and surface waveforms. One way to characterize small scale heterogeneity is to construct random models and confront observed coda waveforms with predictions from these models. Statistical studies of the coda typically rely on models with simplified isotropic and stationary correlation functions in Cartesian geometries. We show how to construct more complex random models for the mantle that can account for arbitrary non-stationary and anisotropic correlation functions as well as for complex geometries. Although this method is computationally heavy, model characteristics such as translational, cylindrical or spherical symmetries can be used to greatly reduce the complexity such that this method becomes practical. With this approach, we can create 3D models of the full spherical Earth that can be radially anisotropic, i.e. with different horizontal and radial correlation functions, and radially non-stationary, i.e. with radially varying model power and correlation functions. Both of these features are crucial for a statistical description of the mantle in which structure depends to first order on the spherical geometry of the Earth. We combine different random model realizations of S velocity with current global tomographic models that are robust at long wavelengths (e.g. Meschede and Romanowicz, 2014, GJI submitted), and compute the effects of these hybrid models on the wavefield with a spectral element code (SPECFEM3D_GLOBE). We finally analyze the resulting coda waves for our model selection and compare our computations with observations. Based on these observations, we make predictions about the strength of unresolved small-scale structure and extrinsic attenuation.

Left Ventricular Function Parameters in a Hispanic Population: Comparison of Planar & Tomographic Radionuclide Ventriculography (MUGA).

PubMed

Martin, Ralph J; Santiago, Bartolo

2015-09-01

Left ventricular (LV) function parameters have major diagnostic and prognostic importance in heart disease. Measurement of ventricular function with tomographic (SPECT) radionuclide ventriculography (MUGA) decreases camera time, improves contrast resolution, accuracy of interpretation and the overall reliability of the study as compared to planar MUGA. The relationship between these techniques is well established particularly with LV ejection fraction (LVEF), while there is limited data comparing the diastolic function parameters. Our goal was to validate the LV function parameters in our Hispanic population. Studies from 44 patients, available from 2009-2010, were retrospectively evaluated. LVEF showed a good correlation between the techniques (r=0.94) with an average difference of 3.8%. In terms of categorizing the results as normal or abnormal, this remained unchanged in 95% of the cases (p=0.035). For the peak filling rate, there was a moderate correlation between the techniques (r=0.71), whereas the diagnosis remained unchanged in 89% of cases (p=0.0004). Time to peak filling values only demonstrated a weak correlation (r=0.22). Nevertheless, the diagnosis remained the same in 68% of the cases (p=0.089). Systolic function results in our study were well below the 7-10% difference reported in the literature. Only a weak to moderate correlation was observed with the diastolic function parameters. Comparison with echocardiogram (not available) may be of benefit to evaluate which of these techniques results in more accurate diastolic function parameters.

3D galaxy clustering with future wide-field surveys: Advantages of a spherical Fourier-Bessel analysis

NASA Astrophysics Data System (ADS)

Lanusse, F.; Rassat, A.; Starck, J.-L.

2015-06-01

Context. Upcoming spectroscopic galaxy surveys are extremely promising to help in addressing the major challenges of cosmology, in particular in understanding the nature of the dark universe. The strength of these surveys, naturally described in spherical geometry, comes from their unprecedented depth and width, but an optimal extraction of their three-dimensional information is of utmost importance to best constrain the properties of the dark universe. Aims: Although there is theoretical motivation and novel tools to explore these surveys using the 3D spherical Fourier-Bessel (SFB) power spectrum of galaxy number counts Cℓ(k,k'), most survey optimisations and forecasts are based on the tomographic spherical harmonics power spectrum C(ij)_ℓ. The goal of this paper is to perform a new investigation of the information that can be extracted from these two analyses in the context of planned stage IV wide-field galaxy surveys. Methods: We compared tomographic and 3D SFB techniques by comparing the forecast cosmological parameter constraints obtained from a Fisher analysis. The comparison was made possible by careful and coherent treatment of non-linear scales in the two analyses, which makes this study the first to compare 3D SFB and tomographic constraints on an equal footing. Nuisance parameters related to a scale- and redshift-dependent galaxy bias were also included in the computation of the 3D SFB and tomographic power spectra for the first time. Results: Tomographic and 3D SFB methods can recover similar constraints in the absence of systematics. This requires choosing an optimal number of redshift bins for the tomographic analysis, which we computed to be N = 26 for zmed ≃ 0.4, N = 30 for zmed ≃ 1.0, and N = 42 for zmed ≃ 1.7. When marginalising over nuisance parameters related to the galaxy bias, the forecast 3D SFB constraints are less affected by this source of systematics than the tomographic constraints. In addition, the rate of increase of the figure of merit as a function of median redshift is higher for the 3D SFB method than for the 2D tomographic method. Conclusions: Constraints from the 3D SFB analysis are less sensitive to unavoidable systematics stemming from a redshift- and scale-dependent galaxy bias. Even for surveys that are optimised with tomography in mind, a 3D SFB analysis is more powerful. In addition, for survey optimisation, the figure of merit for the 3D SFB method increases more rapidly with redshift, especially at higher redshifts, suggesting that the 3D SFB method should be preferred for designing and analysing future wide-field spectroscopic surveys. CosmicPy, the Python package developed for this paper, is freely available at https://cosmicpy.github.io. Appendices are available in electronic form at http://www.aanda.org

Surface Wave Tomography with Spatially Varying Smoothing Based on Continuous Model Regionalization

NASA Astrophysics Data System (ADS)

Liu, Chuanming; Yao, Huajian

2017-03-01

Surface wave tomography based on continuous regionalization of model parameters is widely used to invert for 2-D phase or group velocity maps. An inevitable problem is that the distribution of ray paths is far from homogeneous due to the spatially uneven distribution of stations and seismic events, which often affects the spatial resolution of the tomographic model. We present an improved tomographic method with a spatially varying smoothing scheme that is based on the continuous regionalization approach. The smoothness of the inverted model is constrained by the Gaussian a priori model covariance function with spatially varying correlation lengths based on ray path density. In addition, a two-step inversion procedure is used to suppress the effects of data outliers on tomographic models. Both synthetic and real data are used to evaluate this newly developed tomographic algorithm. In the synthetic tests, when the contrived model has different scales of anomalies but with uneven ray path distribution, we compare the performance of our spatially varying smoothing method with the traditional inversion method, and show that the new method is capable of improving the recovery in regions of dense ray sampling. For real data applications, the resulting phase velocity maps of Rayleigh waves in SE Tibet produced using the spatially varying smoothing method show similar features to the results with the traditional method. However, the new results contain more detailed structures and appears to better resolve the amplitude of anomalies. From both synthetic and real data tests we demonstrate that our new approach is useful to achieve spatially varying resolution when used in regions with heterogeneous ray path distribution.

Evolution of cystic fibrosis lung function in the early years.

PubMed

Bush, Andrew; Sly, Peter D

2015-11-01

Most treatment of newborn screening-diagnosed cystic fibrosis is not evidence-based; there are very few randomized controlled trials (RCTs). Furthermore, the advent of novel molecular therapies, which could be started at diagnosis, mandates performing RCTs in very young children. However, unless the natural history of early cystic fibrosis lung disease is known, RCTs are impossible. Here, we review the results of two large prospective cohorts of these infants - London Cystic Fibrosis Collaboration (LCFC) (London, UK) and Australian Respiratory Early Surveillance Team for Cystic Fibrosis (AREST-CF) (Australia). Nutritional status remained excellent in both the cohorts. Both cohorts reported abnormal lung function aged at 3 months. AREST-CF, which previously reported rapidly declining preschool lung function, now report good conventional school-age spirometry. LCFC reported improvement between 3 months and 1 year, and stability in the second year. AREST-CF also reported a high prevalence of high resolution computed tomographic abnormalities related to free neutrophil elastase in bronchoalveolar lavage; LCFC reported high resolution computed tomographic changes at 1 year, which were too mild to be scored reproducibly. At least in the first 2 years of life, lung function is not a good end-point for RCTs; routine bronchoalveolar lavage and HRCT cannot be justified. Newborn screening has greatly improved outcomes, but we need better point-of-care biomarkers.

Murder, insanity, and medical expert witnesses.

PubMed

Ciccone, J R

1992-06-01

Recent advances in the ability to study brain anatomy and function and attempts to link these findings with human behavior have captured the attention of the legal system. This had led to the increasing use of the "neurological defense" to support a plea of not guilty by reason of insanity. This article explores the history of the insanity defense and explores the role of the medical expert witnesses in integrating clinical and laboratory findings, eg, computed tomographic scans, magnetic resonance scans, and single-photon emission computed tomographic scans. Three cases involving murder and brain dysfunction are discussed: the first case involves a subarachnoid hemorrhage resulting in visual perceptual and memory impairment; the second case, a diagnosis of Alzheimer's disease; and the third case, the controverted diagnosis of complex partial seizures in a serial killer.

A new apparatus for electron tomography in the scanning electron microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morandi, V., E-mail: morandi@bo.imm.cnr.it; Maccagnani, P.; Masini, L.

2015-06-23

The three-dimensional reconstruction of a microscopic specimen has been obtained by applying the tomographic algorithm to a set of images acquired in a Scanning Electron Microscope. This result was achieved starting from a series of projections obtained by stepwise rotating the sample under the beam raster. The Scanning Electron Microscope was operated in the scanning-transmission imaging mode, where the intensity of the transmitted electron beam is a monotonic function of the local mass-density and thickness of the specimen. The detection strategy has been implemented and tailored in order to maintain the projection requirement over the large tilt range, as requiredmore » by the tomographic workflow. A Si-based electron detector and an eucentric-rotation specimen holder have been specifically developed for the purpose.« less

Three-dimensional Image Reconstruction in J-PET Using Filtered Back-projection Method

NASA Astrophysics Data System (ADS)

Shopa, R. Y.; Klimaszewski, K.; Kowalski, P.; Krzemień, W.; Raczyński, L.; Wiślicki, W.; Białas, P.; Curceanu, C.; Czerwiński, E.; Dulski, K.; Gajos, A.; Głowacz, B.; Gorgol, M.; Hiesmayr, B.; Jasińska, B.; Kisielewska-Kamińska, D.; Korcyl, G.; Kozik, T.; Krawczyk, N.; Kubicz, E.; Mohammed, M.; Pawlik-Niedźwiecka, M.; Niedźwiecki, S.; Pałka, M.; Rudy, Z.; Sharma, N. G.; Sharma, S.; Silarski, M.; Skurzok, M.; Wieczorek, A.; Zgardzińska, B.; Zieliński, M.; Moskal, P.

We present a method and preliminary results of the image reconstruction in the Jagiellonian PET tomograph. Using GATE (Geant4 Application for Tomographic Emission), interactions of the 511 keV photons with a cylindrical detector were generated. Pairs of such photons, flying back-to-back, originate from e+e- annihilations inside a 1-mm spherical source. Spatial and temporal coordinates of hits were smeared using experimental resolutions of the detector. We incorporated the algorithm of the 3D Filtered Back Projection, implemented in the STIR and TomoPy software packages, which differ in approximation methods. Consistent results for the Point Spread Functions of ~5/7,mm and ~9/20, mm were obtained, using STIR, for transverse and longitudinal directions, respectively, with no time of flight information included.

Use of new minimum intervention dentistry technologies in caries management.

PubMed

Tassery, H; Levallois, B; Terrer, E; Manton, D J; Otsuki, M; Koubi, S; Gugnani, N; Panayotov, I; Jacquot, B; Cuisinier, F; Rechmann, P

2013-06-01

Preservation of natural tooth structure requires early detection of the carious lesion and is associated with comprehensive patient dental care. Processes aiming to detect carious lesions in the initial stage with optimum efficiency employ a variety of technologies such as magnifying loupes, transillumination, light and laser fluorescence (QLF® and DIAGNOdent® ) and autofluorescence (Soprolife® and VistaCam®), electric current/impedance (CarieScan(®) ), tomographic imaging and image processing. Most fluorescent caries detection tools can discriminate between healthy and carious dental tissue, demonstrating different levels of sensitivity and specificity. Based on the fluorescence principle, an LED camera (Soprolife® ) was developed (Sopro-Acteon, La Ciotat, France) which combined magnification, fluorescence, picture acquisition and an innovative therapeutic concept called light-induced fluorescence evaluator for diagnosis and treatment (LIFEDT). This article is rounded off by a Soprolife® illustration about minimally or even non-invasive dental techniques, distinguishing those that preserve or reinforce the enamel and enamel-dentine structures without any preparation (MIT1- minimally invasive therapy 1) from those that require minimum preparation of the dental tissues (MIT2 - minimally invasive therapy 2) using several clinical cases as examples. MIT1 encompasses all the dental techniques aimed at disinfection, remineralizing, reversing and sealing the caries process and MIT2 involves a series of specific tools, including microburs, air abrasion devices, sonic and ultrasonic inserts and photo-activated disinfection to achieve minimal preparation of the tooth. With respect to minimally invasive treatment and prevention, the use of lasers is discussed. Furthermore, while most practices operate under a surgical model, Caries Management by Risk Assessment (CaMBRA) encourages a medical model of disease prevention and management to control the manifestation of the disease, or keep the oral environment in a state of balance between pathological and preventive factors. Early detection and diagnosis and prediction of lesion activity are of great interest and may change traditional operative procedures substantially. Fluorescence tools with high levels of magnification and observational capacity should guide clinicians towards a more preventive and minimally invasive treatment strategy. © 2013 Australian Dental Association.

A Tomographic Method for the Reconstruction of Local Probability Density Functions

NASA Technical Reports Server (NTRS)

Sivathanu, Y. R.; Gore, J. P.

1993-01-01

A method of obtaining the probability density function (PDF) of local properties from path integrated measurements is described. The approach uses a discrete probability function (DPF) method to infer the PDF of the local extinction coefficient from measurements of the PDFs of the path integrated transmittance. The local PDFs obtained using the method are compared with those obtained from direct intrusive measurements in propylene/air and ethylene/air diffusion flames. The results of this comparison are good.

Tomographic Imaging of a Forested Area By Airborne Multi-Baseline P-Band SAR.

PubMed

Frey, Othmar; Morsdorf, Felix; Meier, Erich

2008-09-24

In recent years, various attempts have been undertaken to obtain information about the structure of forested areas from multi-baseline synthetic aperture radar data. Tomographic processing of such data has been demonstrated for airborne L-band data but the quality of the focused tomographic images is limited by several factors. In particular, the common Fourierbased focusing methods are susceptible to irregular and sparse sampling, two problems, that are unavoidable in case of multi-pass, multi-baseline SAR data acquired by an airborne system. In this paper, a tomographic focusing method based on the time-domain back-projection algorithm is proposed, which maintains the geometric relationship between the original sensor positions and the imaged target and is therefore able to cope with irregular sampling without introducing any approximations with respect to the geometry. The tomographic focusing quality is assessed by analysing the impulse response of simulated point targets and an in-scene corner reflector. And, in particular, several tomographic slices of a volume representing a forested area are given. The respective P-band tomographic data set consisting of eleven flight tracks has been acquired by the airborne E-SAR sensor of the German Aerospace Center (DLR).

A cost-utility analysis of the use of preoperative computed tomographic angiography in abdomen-based perforator flap breast reconstruction.

PubMed

Offodile, Anaeze C; Chatterjee, Abhishek; Vallejo, Sergio; Fisher, Carla S; Tchou, Julia C; Guo, Lifei

2015-04-01

Computed tomographic angiography is a diagnostic tool increasingly used for preoperative vascular mapping in abdomen-based perforator flap breast reconstruction. This study compared the use of computed tomographic angiography and the conventional practice of Doppler ultrasonography only in postmastectomy reconstruction using a cost-utility model. Following a comprehensive literature review, a decision analytic model was created using the three most clinically relevant health outcomes in free autologous breast reconstruction with computed tomographic angiography versus Doppler ultrasonography only. Cost and utility estimates for each health outcome were used to derive the quality-adjusted life-years and incremental cost-utility ratio. One-way sensitivity analysis was performed to scrutinize the robustness of the authors' results. Six studies and 782 patients were identified. Cost-utility analysis revealed a baseline cost savings of $3179, a gain in quality-adjusted life-years of 0.25. This yielded an incremental cost-utility ratio of -$12,716, implying a dominant choice favoring preoperative computed tomographic angiography. Sensitivity analysis revealed that computed tomographic angiography was costlier when the operative time difference between the two techniques was less than 21.3 minutes. However, the clinical advantage of computed tomographic angiography over Doppler ultrasonography only showed that computed tomographic angiography would still remain the cost-effective option even if it offered no additional operating time advantage. The authors' results show that computed tomographic angiography is a cost-effective technology for identifying lower abdominal perforators for autologous breast reconstruction. Although the perfect study would be a randomized controlled trial of the two approaches with true cost accrual, the authors' results represent the best available evidence.

RNA aptamers that functionally interact with green fluorescent protein and its derivatives

PubMed Central

Shui, Bo; Ozer, Abdullah; Zipfel, Warren; Sahu, Nevedita; Singh, Avtar; Lis, John T.; Shi, Hua; Kotlikoff, Michael I.

2012-01-01

Green Fluorescent Protein (GFP) and related fluorescent proteins (FPs) have been widely used to tag proteins, allowing their expression and subcellular localization to be examined in real time in living cells and animals. Similar fluorescent methods are highly desirable to detect and track RNA and other biological molecules in living cells. For this purpose, we have developed a group of RNA aptamers that bind GFP and related proteins, which we term Fluorescent Protein-Binding Aptamers (FPBA). These aptamers bind GFP, YFP and CFP with low nanomolar affinity and binding decreases GFP fluorescence, whereas slightly augmenting YFP and CFP brightness. Aptamer binding results in an increase in the pKa of EGFP, decreasing the 475 nm excited green fluorescence at a given pH. We report the secondary structure of FPBA and the ability to synthesize functional multivalent dendrimers. FPBA expressed in live cells decreased GFP fluorescence in a valency-dependent manner, indicating that the RNA aptamers function within cells. The development of aptamers that bind fluorescent proteins with high affinity and alter their function, markedly expands their use in the study of biological pathways. PMID:22189104

Seismic tomography of the southern California crust based on spectral-element and adjoint methods

NASA Astrophysics Data System (ADS)

Tape, Carl; Liu, Qinya; Maggi, Alessia; Tromp, Jeroen

2010-01-01

We iteratively improve a 3-D tomographic model of the southern California crust using numerical simulations of seismic wave propagation based on a spectral-element method (SEM) in combination with an adjoint method. The initial 3-D model is provided by the Southern California Earthquake Center. The data set comprises three-component seismic waveforms (i.e. both body and surface waves), filtered over the period range 2-30 s, from 143 local earthquakes recorded by a network of 203 stations. Time windows for measurements are automatically selected by the FLEXWIN algorithm. The misfit function in the tomographic inversion is based on frequency-dependent multitaper traveltime differences. The gradient of the misfit function and related finite-frequency sensitivity kernels for each earthquake are computed using an adjoint technique. The kernels are combined using a source subspace projection method to compute a model update at each iteration of a gradient-based minimization algorithm. The inversion involved 16 iterations, which required 6800 wavefield simulations. The new crustal model, m16, is described in terms of independent shear (VS) and bulk-sound (VB) wave speed variations. It exhibits strong heterogeneity, including local changes of +/-30 per cent with respect to the initial 3-D model. The model reveals several features that relate to geological observations, such as sedimentary basins, exhumed batholiths, and contrasting lithologies across faults. The quality of the new model is validated by quantifying waveform misfits of full-length seismograms from 91 earthquakes that were not used in the tomographic inversion. The new model provides more accurate synthetic seismograms that will benefit seismic hazard assessment.

Adjoint Tomography of the Southern California Crust (Invited) (Invited)

NASA Astrophysics Data System (ADS)

Tape, C.; Liu, Q.; Maggi, A.; Tromp, J.

2009-12-01

We iteratively improve a three-dimensional tomographic model of the southern California crust using numerical simulations of seismic wave propagation based on a spectral-element method (SEM) in combination with an adjoint method. The initial 3D model is provided by the Southern California Earthquake Center. The dataset comprises three-component seismic waveforms (i.e. both body and surface waves), filtered over the period range 2-30 s, from 143 local earthquakes recorded by a network of 203 stations. Time windows for measurements are automatically selected by the FLEXWIN algorithm. The misfit function in the tomographic inversion is based on frequency-dependent multitaper traveltime differences. The gradient of the misfit function and related finite-frequency sensitivity kernels for each earthquake are computed using an adjoint technique. The kernels are combined using a source subspace projection method to compute a model update at each iteration of a gradient-based minimization algorithm. The inversion involved 16 iterations, which required 6800 wavefield simulations and a total of 0.8 million CPU hours. The new crustal model, m16, is described in terms of independent shear (Vs) and bulk-sound (Vb) wavespeed variations. It exhibits strong heterogeneity, including local changes of ±30% with respect to the initial 3D model. The model reveals several features that relate to geologic observations, such as sedimentary basins, exhumed batholiths, and contrasting lithologies across faults. The quality of the new model is validated by quantifying waveform misfits of full-length seismograms from 91 earthquakes that were not used in the tomographic inversion. The new model provides more accurate synthetic seismograms that will benefit seismic hazard assessment.

Fluorescence Quantum Yield Measurements of Fluorescent Proteins: A Laboratory Experiment for a Biochemistry or Molecular Biophysics Laboratory Course

ERIC Educational Resources Information Center

Wall, Kathryn P.; Dillon, Rebecca; Knowles, Michelle K.

2015-01-01

Fluorescent proteins are commonly used in cell biology to assess where proteins are within a cell as a function of time and provide insight into intracellular protein function. However, the usefulness of a fluorescent protein depends directly on the quantum yield. The quantum yield relates the efficiency at which a fluorescent molecule converts…

FLIM FRET Technology for Drug Discovery: Automated Multiwell-Plate High-Content Analysis, Multiplexed Readouts and Application in Situ**

PubMed Central

Kumar, Sunil; Alibhai, Dominic; Margineanu, Anca; Laine, Romain; Kennedy, Gordon; McGinty, James; Warren, Sean; Kelly, Douglas; Alexandrov, Yuriy; Munro, Ian; Talbot, Clifford; Stuckey, Daniel W; Kimberly, Christopher; Viellerobe, Bertrand; Lacombe, Francois; Lam, Eric W-F; Taylor, Harriet; Dallman, Margaret J; Stamp, Gordon; Murray, Edward J; Stuhmeier, Frank; Sardini, Alessandro; Katan, Matilda; Elson, Daniel S; Neil, Mark A A; Dunsby, Chris; French, Paul M W

2011-01-01

A fluorescence lifetime imaging (FLIM) technology platform intended to read out changes in Förster resonance energy transfer (FRET) efficiency is presented for the study of protein interactions across the drug-discovery pipeline. FLIM provides a robust, inherently ratiometric imaging modality for drug discovery that could allow the same sensor constructs to be translated from automated cell-based assays through small transparent organisms such as zebrafish to mammals. To this end, an automated FLIM multiwell-plate reader is described for high content analysis of fixed and live cells, tomographic FLIM in zebrafish and FLIM FRET of live cells via confocal endomicroscopy. For cell-based assays, an exemplar application reading out protein aggregation using FLIM FRET is presented, and the potential for multiple simultaneous FLIM (FRET) readouts in microscopy is illustrated. PMID:21337485

Deformable 3D-2D registration for CT and its application to low dose tomographic fluoroscopy

NASA Astrophysics Data System (ADS)

Flach, Barbara; Brehm, Marcus; Sawall, Stefan; Kachelrieß, Marc

2014-12-01

Many applications in medical imaging include image registration for matching of images from the same or different modalities. In the case of full data sampling, the respective reconstructed images are usually of such a good image quality that standard deformable volume-to-volume (3D-3D) registration approaches can be applied. But research in temporal-correlated image reconstruction and dose reductions increases the number of cases where rawdata are available from only few projection angles. Here, deteriorated image quality leads to non-acceptable deformable volume-to-volume registration results. Therefore a registration approach is required that is robust against a decreasing number of projections defining the target position. We propose a deformable volume-to-rawdata (3D-2D) registration method that aims at finding a displacement vector field maximizing the alignment of a CT volume and the acquired rawdata based on the sum of squared differences in rawdata domain. The registration is constrained by a regularization term in accordance with a fluid-based diffusion. Both cost function components, the rawdata fidelity and the regularization term, are optimized in an alternating manner. The matching criterion is optimized by a conjugate gradient descent for nonlinear functions, while the regularization is realized by convolution of the vector fields with Gaussian kernels. We validate the proposed method and compare it to the demons algorithm, a well-known 3D-3D registration method. The comparison is done for a range of 4-60 target projections using datasets from low dose tomographic fluoroscopy as an application example. The results show a high correlation to the ground truth target position without introducing artifacts even in the case of very few projections. In particular the matching in the rawdata domain is improved compared to the 3D-3D registration for the investigated range. The proposed volume-to-rawdata registration increases the robustness regarding sparse rawdata and provides more stable results than volume-to-volume approaches. By applying the proposed registration approach to low dose tomographic fluoroscopy it is possible to improve the temporal resolution and thus to increase the robustness of low dose tomographic fluoroscopy.

Tomographic Reconstruction from a Few Views: A Multi-Marginal Optimal Transport Approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abraham, I., E-mail: isabelle.abraham@cea.fr; Abraham, R., E-mail: romain.abraham@univ-orleans.fr; Bergounioux, M., E-mail: maitine.bergounioux@univ-orleans.fr

2017-02-15

In this article, we focus on tomographic reconstruction. The problem is to determine the shape of the interior interface using a tomographic approach while very few X-ray radiographs are performed. We use a multi-marginal optimal transport approach. Preliminary numerical results are presented.

Development of fluorescent probes based on protection-deprotection of the key functional groups for biological imaging.

PubMed

Tang, Yonghe; Lee, Dayoung; Wang, Jiaoliang; Li, Guanhan; Yu, Jinghua; Lin, Weiying; Yoon, Juyoung

2015-08-07

Recently, the strategy of protection-deprotection of functional groups has been widely employed to design fluorescent probes, as the protection-deprotection of functional groups often induces a marked change in electronic properties. Significant advances have been made in the development of analyte-responsive fluorescent probes based on the protection-deprotection strategy. In this tutorial review, we highlight the representative examples of small-molecule based fluorescent probes for bioimaging, which are operated via the protection-deprotection of key functional groups such as aldehyde, hydroxyl, and amino functional groups reported from 2010 to 2014. The discussion includes the general protection-deprotection methods for aldehyde, hydroxyl, or amino groups, as well as the design strategies, sensing mechanisms, and deprotection modes of the representative fluorescent imaging probes applied to bio-imaging.

Extracting the time scales of conformational dynamics from single-molecule single-photon fluorescence statistics.

PubMed

Shang, Jianyuan; Geva, Eitan

2007-04-26

The quenching rate of a fluorophore attached to a macromolecule can be rather sensitive to its conformational state. The decay of the corresponding fluorescence lifetime autocorrelation function can therefore provide unique information on the time scales of conformational dynamics. The conventional way of measuring the fluorescence lifetime autocorrelation function involves evaluating it from the distribution of delay times between photoexcitation and photon emission. However, the time resolution of this procedure is limited by the time window required for collecting enough photons in order to establish this distribution with sufficient signal-to-noise ratio. Yang and Xie have recently proposed an approach for improving the time resolution, which is based on the argument that the autocorrelation function of the delay time between photoexcitation and photon emission is proportional to the autocorrelation function of the square of the fluorescence lifetime [Yang, H.; Xie, X. S. J. Chem. Phys. 2002, 117, 10965]. In this paper, we show that the delay-time autocorrelation function is equal to the autocorrelation function of the square of the fluorescence lifetime divided by the autocorrelation function of the fluorescence lifetime. We examine the conditions under which the delay-time autocorrelation function is approximately proportional to the autocorrelation function of the square of the fluorescence lifetime. We also investigate the correlation between the decay of the delay-time autocorrelation function and the time scales of conformational dynamics. The results are demonstrated via applications to a two-state model and an off-lattice model of a polypeptide.

Simultaneous multi-headed imager geometry calibration method

DOEpatents

Tran, Vi-Hoa [Newport News, VA; Meikle, Steven Richard [Penshurst, AU; Smith, Mark Frederick [Yorktown, VA

2008-02-19

A method for calibrating multi-headed high sensitivity and high spatial resolution dynamic imaging systems, especially those useful in the acquisition of tomographic images of small animals. The method of the present invention comprises: simultaneously calibrating two or more detectors to the same coordinate system; and functionally correcting for unwanted detector movement due to gantry flexing.

Markov chain Monte Carlo estimation of quantum states

NASA Astrophysics Data System (ADS)

Diguglielmo, James; Messenger, Chris; Fiurášek, Jaromír; Hage, Boris; Samblowski, Aiko; Schmidt, Tabea; Schnabel, Roman

2009-03-01

We apply a Bayesian data analysis scheme known as the Markov chain Monte Carlo to the tomographic reconstruction of quantum states. This method yields a vector, known as the Markov chain, which contains the full statistical information concerning all reconstruction parameters including their statistical correlations with no a priori assumptions as to the form of the distribution from which it has been obtained. From this vector we can derive, e.g., the marginal distributions and uncertainties of all model parameters, and also of other quantities such as the purity of the reconstructed state. We demonstrate the utility of this scheme by reconstructing the Wigner function of phase-diffused squeezed states. These states possess non-Gaussian statistics and therefore represent a nontrivial case of tomographic reconstruction. We compare our results to those obtained through pure maximum-likelihood and Fisher information approaches.

Fast tomosynthesis for lung cancer detection using the SBDX geometry

NASA Astrophysics Data System (ADS)

Fahrig, Rebecca; Pineda, Angel R.; Solomon, Edward G.; Leung, Ann N.; Pelc, Norbert J.

2003-06-01

Radiology-based lung-cancer detection is a high-contrast imaging task, consisting of the detection of a small mass of tissue within much lower density lung parenchyma. This imaging task requires removal of confounding image details, fast image acquisition (< 0.1 s for pericardial region), low dose (comparable to a chest x-ray), high resolution (< 0.25 mm in-plane) and patient positioning flexibility. We present an investigation of tomosynthesis, implemented using the Scanning-Beam Digital X-ray System (SBDX), to achieve these goals. We designed an image-based computer model of tomosynthesis using a high-resolution (0.15-mm isotropic voxels), low-noise CT volume image of a lung phantom, numerically added spherical lesions and convolution-based tomographic blurring. Lesion visibility was examined as a function of half-tomographic angle for 2.5 and 4.0 mm diameter lesions. Gaussian distributed noise was added to the projected images. For lesions 2.5 mm and 4.0 mm in diameter, half-tomographic angles of at least 6° and 9° respectively were necessary before visualization of the lesions improved. The addition of noise for a dose equivalent to 1/10 that used for a standard chest radiograph did not significantly impair lesion detection. The results are promising, indicating that lung-cancer detection using a modified SBDX system is possible.

Measurement of radioactivity concentration in blood by using newly developed ToT LuAG-APD based small animal PET tomograph.

PubMed

Malik, Azhar H; Shimazoe, Kenji; Takahashi, Hiroyuki

2013-01-01

In order to obtain plasma time activity curve (PTAC), input function for almost all quantitative PET studies, patient blood is sampled manually from the artery or vein which has various drawbacks. Recently a novel compact Time over Threshold (ToT) based Pr:LuAG-APD animal PET tomograph is developed in our laboratory which has 10% energy resolution, 4.2 ns time resolution and 1.76 mm spatial resolution. The measured value of spatial resolution shows much promise for imaging the blood vascular, i.e; artery of diameter 2.3-2.4mm, and hence, to measure PTAC for quantitative PET studies. To find the measurement time required to obtain reasonable counts for image reconstruction, the most important parameter is the sensitivity of the system. Usually small animal PET systems are characterized by using a point source in air. We used Electron Gamma Shower 5 (EGS5) code to simulate a point source at different positions inside the sensitive volume of tomograph and the axial and radial variations in the sensitivity are studied in air and phantom equivalent water cylinder. An average sensitivity difference of 34% in axial direction and 24.6% in radial direction is observed when point source is displaced inside water cylinder instead of air.

3D tomographic imaging with the γ-eye planar scintigraphic gamma camera

NASA Astrophysics Data System (ADS)

Tunnicliffe, H.; Georgiou, M.; Loudos, G. K.; Simcox, A.; Tsoumpas, C.

2017-11-01

γ-eye is a desktop planar scintigraphic gamma camera (100 mm × 50 mm field of view) designed by BET Solutions as an affordable tool for dynamic, whole body, small-animal imaging. This investigation tests the viability of using γ-eye for the collection of tomographic data for 3D SPECT reconstruction. Two software packages, QSPECT and STIR (software for tomographic image reconstruction), have been compared. Reconstructions have been performed using QSPECT’s implementation of the OSEM algorithm and STIR’s OSMAPOSL (Ordered Subset Maximum A Posteriori One Step Late) and OSSPS (Ordered Subsets Separable Paraboloidal Surrogate) algorithms. Reconstructed images of phantom and mouse data have been assessed in terms of spatial resolution, sensitivity to varying activity levels and uniformity. The effect of varying the number of iterations, the voxel size (1.25 mm default voxel size reduced to 0.625 mm and 0.3125 mm), the point spread function correction and the weight of prior terms were explored. While QSPECT demonstrated faster reconstructions, STIR outperformed it in terms of resolution (as low as 1 mm versus 3 mm), particularly when smaller voxel sizes were used, and in terms of uniformity, particularly when prior terms were used. Little difference in terms of sensitivity was seen throughout.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raymund, T.D.

Recently, several tomographic techniques for ionospheric electron density imaging have been proposed. These techniques reconstruct a vertical slice image of electron density using total electron content data. The data are measured between a low orbit beacon satellite and fixed receivers located along the projected orbital path of the satellite. By using such tomographic techniques, it may be possible to inexpensively (relative to incoherent scatter techniques) image the ionospheric electron density in a vertical plane several times per day. The satellite and receiver geometry used to measure the total electron content data causes the data to be incomplete; that is, themore » measured data do not contain enough information to completely specify the ionospheric electron density distribution in the region between the satellite and the receivers. A new algorithm is proposed which allows the incorporation of other complementary measurements, such as those from ionosondes, and also includes ways to include a priori information about the unknown electron density distribution in the reconstruction process. The algorithm makes use of two-dimensional basis functions. Illustrative application of this algorithm is made to simulated cases with good results. The technique is also applied to real total electron content (TEC) records collected in Scandinavia in conjunction with the EISCAT incoherent scatter radar. The tomographic reconstructions are compared with the incoherent scatter electron density images of the same region of the ionosphere.« less

Red Fluorescent Carbon Nanoparticle-Based Cell Imaging Probe.

PubMed

Ali, Haydar; Bhunia, Susanta Kumar; Dalal, Chumki; Jana, Nikhil R

2016-04-13

Fluorescent carbon nanoparticle-based probes with tunable visible emission are biocompatible, environment friendly and most suitable for various biomedical applications. However, synthesis of red fluorescent carbon nanoparticles and their transformation into functional nanoparticles are very challenging. Here we report red fluorescent carbon nanoparticle-based nanobioconjugates of <25 nm hydrodynamic size and their application as fluorescent cell labels. Hydrophobic carbon nanoparticles are synthesized via high temperature colloid-chemical approach and transformed into water-soluble functional nanoparticles via coating with amphiphilic polymer followed by covalent linking with desired biomolecules. Following this approach, carbon nanoparticles are functionalized with polyethylene glycol, primary amine, glucose, arginine, histidine, biotin and folic acid. These functional nanoparticles can be excited with blue/green light (i.e., 400-550 nm) to capture their emission spanning from 550 to 750 nm. Arginine and folic acid functionalized nanoparticles have been demonstrated as fluorescent cell labels where blue and green excitation has been used for imaging of labeled cells. The presented method can be extended for the development of carbon nanoparticle-based other bioimaging probes.

Breaking the acoustic diffraction barrier with localization optoacoustic tomography

NASA Astrophysics Data System (ADS)

Deán-Ben, X. Luís.; Razansky, Daniel

2018-02-01

Diffraction causes blurring of high-resolution features in images and has been traditionally associated to the resolution limit in light microscopy and other imaging modalities. The resolution of an imaging system can be generally assessed via its point spread function, corresponding to the image acquired from a point source. However, the precision in determining the position of an isolated source can greatly exceed the diffraction limit. By combining the estimated positions of multiple sources, localization-based imaging has resulted in groundbreaking methods such as super-resolution fluorescence optical microscopy and has also enabled ultrasound imaging of microvascular structures with unprecedented spatial resolution in deep tissues. Herein, we introduce localization optoacoustic tomography (LOT) and discuss on the prospects of using localization imaging principles in optoacoustic imaging. LOT was experimentally implemented by real-time imaging of flowing particles in 3D with a recently-developed volumetric optoacoustic tomography system. Provided the particles were separated by a distance larger than the diffraction-limited resolution, their individual locations could be accurately determined in each frame of the acquired image sequence and the localization image was formed by superimposing a set of points corresponding to the localized positions of the absorbers. The presented results demonstrate that LOT can significantly enhance the well-established advantages of optoacoustic imaging by breaking the acoustic diffraction barrier in deep tissues and mitigating artifacts due to limited-view tomographic acquisitions.

Can organic matter hide from decomposers in the labyrinth of soil aggregates? Micro-engineered Soil Chips challenging foraging fungi

NASA Astrophysics Data System (ADS)

Hammer, Edith C.; Aleklett, Kristin; Arellano Caicedo, Carlos G.; Bengtsson, Martin; Micaela Mafla Endara, Paola; Ohlsson, Pelle

2017-04-01

From the point of view of microorganisms, the soil environment is an enormously complex labyrinth with paths and dead-end streets, where resources and shelters are unevenly distributed. We study foraging strategies of soil organisms, especially fungi, and the possibility of physio-spatial stabilization of organic matter by "hiding" in occluded soil spaces. We manipulate growth habitat microstructure with lab-on-a-chip techniques, where we designed complex environments with channels and obstacle at dimensions of the size of hyphae, and construct them in the transparent, gas-permeable polymer PDMS. We fill those with different nutrient solutions or combine with mineral nutrient gradients, and inoculate them with soil organisms. We analyze organisms and substrates with microscopy, fluorescence microscopy and analytical chemistry. We compared different soil litter decomposers and an arbuscular mycorrhizal fungus for their ability to forage through complex air-gap structures and attempt to classify them into functional traits concerning their mycelium directionality, space-exploring approach and ability to grow through acute angles and narrow constrictions. We identified structures which are very difficult to penetrate for most species, and compounds located behind such features may thus be spatially unavailable for decomposers. We discuss our approach in comparison to soil pore space tomographic analyses and findings we made in the pore space of colonized wood biochar.

Low dose tomographic fluoroscopy: 4D intervention guidance with running prior

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flach, Barbara; Kuntz, Jan; Brehm, Marcus

Purpose: Today's standard imaging technique in interventional radiology is the single- or biplane x-ray fluoroscopy which delivers 2D projection images as a function of time (2D+T). This state-of-the-art technology, however, suffers from its projective nature and is limited by the superposition of the patient's anatomy. Temporally resolved tomographic volumes (3D+T) would significantly improve the visualization of complex structures. A continuous tomographic data acquisition, if carried out with today's technology, would yield an excessive patient dose. Recently the authors proposed a method that enables tomographic fluoroscopy at the same dose level as projective fluoroscopy which means that if scanning time ofmore » an intervention guided by projective fluoroscopy is the same as that of an intervention guided by tomographic fluoroscopy, almost the same dose is administered to the patient. The purpose of this work is to extend authors' previous work and allow for patient motion during the intervention.Methods: The authors propose the running prior technique for adaptation of a prior image. This adaptation is realized by a combination of registration and projection replacement. In a first step the prior is deformed to the current position via affine and deformable registration. Then the information from outdated projections is replaced by newly acquired projections using forward and backprojection steps. The thus adapted volume is the running prior. The proposed method is validated by simulated as well as measured data. To investigate motion during intervention a moving head phantom was simulated. Real in vivo data of a pig are acquired by a prototype CT system consisting of a flat detector and a continuously rotating clinical gantry.Results: With the running prior technique it is possible to correct for motion without additional dose. For an application in intervention guidance both steps of the running prior technique, registration and replacement, are necessary. Reconstructed volumes based on the running prior show high image quality without introducing new artifacts and the interventional materials are displayed at the correct position.Conclusions: The running prior improves the robustness of low dose 3D+T intervention guidance toward intended or unintended patient motion.« less

New Developments in Hard X-ray Fluorescence Microscopy for In-situ Investigations of Trace Element Distributions in Aqueous Systems of Soil Colloids

NASA Astrophysics Data System (ADS)

Gleber, Sophie-Charlotte; Weinhausen, Britta; Köster, Sarah; Ward, Jesse; Vine, David; Finney, Lydia; Vogt, Stefan

2013-10-01

The distribution, binding and release of trace elements on soil colloids determine matter transport through the soil matrix, and necessitates an aqueous environment and short length and time scales for their study. However, not many microscopy techniques allow for that. We previously showed hard x-ray fluorescence microscopy capabilities to image aqueous colloidal soil samples [1]. As this technique provides attogram sensitivity for transition elements like Cu, Zn, and other geochemically relevant trace elements at sub micrometer spatial resolution (currently down to 150 nm at 2-ID-E [2]; below 50nm at Bionanoprobe, cf. G.Woloschak et al, this volume) combined with the capability to penetrate tens of micrometer of water, it is ideally suited for imaging the elemental content of soil colloids. To address the question of binding and release processes of trace elements on the surface of soil colloids, we developed a microfluidics based XRF flow cytometer, and expanded the applied methods of hard x-ray fluorescence microscopy towards three dimensional imaging. Here, we show (a) the 2-D imaged distributions of Si, K and Fe on soil colloids of Pseudogley samples; (b) how the trace element distribution is a dynamic, pH-dependent process; and (c) x-ray tomographic applications to render the trace elemental distributions in 3-D. We conclude that the approach presented here shows the remarkable potential to image and quantitate elemental distributions from samles within their natural aqueous microenvironment, particularly important in the environmental, medical, and biological sciences.

Multimodal Fluorescence and Bioluminescence Imaging Reveals Transfection Potential of Intratracheally Administered Polyplexes for Breast Cancer Lung Metastases.

PubMed

Geyer, Antonia; Taschauer, Alexander; Alioglu, Fatih; Anton, Martina; Maier, Julia; Drothler, Elisabeth; Simlinger, Manuela; Yavuz, Sümeyye; Sami, Haider; Ogris, Manfred

2017-12-01

Local delivery of anticancer agents or gene therapeutics to lung tumors can circumvent side effects or accumulation in non-target organs, but accessibility via the alveolar side of the blood-air barrier remains challenging. Polyplexes based on plasmid and linear polyethylenimine (LPEI) transfect healthy lung tissue when applied intravenously (i.v.) in the mouse, but direct delivery into the lungs results in low transfection of lung tissue. Nevertheless, LPEI could offer the potential to transfect lung tumors selectively, if accessible from the alveolar side. This study combined near infrared fluorescent protein 720 (iRFP720) and firefly luciferase as reporter genes for detection of tumor lesions and transfection efficiency of LPEI polyplexes, after intratracheal microspraying in mice bearing 4T1 triple negative breast cancer lung metastases. Simultaneous flow cytometric analysis of iRFP720 and enhanced green fluorescent protein expression in vitro demonstrated the potential to combine these reporter genes within transfection studies. Polyplex biophysics was characterized by single nanoparticle tracking analysis (NTA) to monitor physical integrity after microspraying in vitro. 4T1 cells were transduced with iRFP720-encoding lentivirus and evaluated by flow cytometry for stable iRFP720 expression. Growth of 4T1-iRFP720 cells was monitored in Balb/c mice by tomographic near infrared imaging, tissue and tumor morphology by computed tomography and magnetic resonance imaging. In 4T1-iRFP720 tumor-bearing mice, intratracheal administration of luciferase-encoding plasmid DNA by LPEI polyplexes resulted in successful tumor transfection, as revealed by bioluminescence imaging.

Laser injury and in vivo multimodal imaging using a mouse model

NASA Astrophysics Data System (ADS)

Pocock, Ginger M.; Boretsky, Adam; Gupta, Praveena; Oliver, Jeff W.; Motamedi, Massoud

2011-03-01

Balb/c wild type mice were used to perform in vivo experiments of laser-induced thermal damage to the retina. A Heidelberg Spectralis HRA confocal scanning laser ophthalmoscope with a spectral domain optical coherence tomographer was used to obtain fundus and cross-sectional images of laser induced injury in the retina. Sub-threshold, threshold, and supra-threshold lesions were observed using optical coherence tomography (OCT), infrared reflectance, red-free reflectance, fluorescence angiography, and autofluorescence imaging modalities at different time points post-exposure. Lesions observed using all imaging modalities, except autofluorescence, were not visible immediately after exposure but did resolve within an hour and grew in size over a 24 hour period. There was a decrease in fundus autofluorescence at exposure sites immediately following exposure that developed into hyper-fluorescence 24-48 hours later. OCT images revealed threshold damage that was localized to the RPE but extended into the neural retina over a 24 hour period. Volumetric representations of the mouse retina were created to visualize the extent of damage within the retina over a 24 hour period. Multimodal imaging provides complementary information regarding damage mechanisms that may be used to quantify the extent of the damage as well as the effectiveness of treatments without need for histology.

Direct reconstruction of pharmacokinetic parameters in dynamic fluorescence molecular tomography by the augmented Lagrangian method

NASA Astrophysics Data System (ADS)

Zhu, Dianwen; Zhang, Wei; Zhao, Yue; Li, Changqing

2016-03-01

Dynamic fluorescence molecular tomography (FMT) has the potential to quantify physiological or biochemical information, known as pharmacokinetic parameters, which are important for cancer detection, drug development and delivery etc. To image those parameters, there are indirect methods, which are easier to implement but tend to provide images with low signal-to-noise ratio, and direct methods, which model all the measurement noises together and are statistically more efficient. The direct reconstruction methods in dynamic FMT have attracted a lot of attention recently. However, the coupling of tomographic image reconstruction and nonlinearity of kinetic parameter estimation due to the compartment modeling has imposed a huge computational burden to the direct reconstruction of the kinetic parameters. In this paper, we propose to take advantage of both the direct and indirect reconstruction ideas through a variable splitting strategy under the augmented Lagrangian framework. Each iteration of the direct reconstruction is split into two steps: the dynamic FMT image reconstruction and the node-wise nonlinear least squares fitting of the pharmacokinetic parameter images. Through numerical simulation studies, we have found that the proposed algorithm can achieve good reconstruction results within a small amount of time. This will be the first step for a combined dynamic PET and FMT imaging in the future.

System and method for generating motion corrected tomographic images

DOEpatents

Gleason, Shaun S [Knoxville, TN; Goddard, Jr., James S.

2012-05-01

A method and related system for generating motion corrected tomographic images includes the steps of illuminating a region of interest (ROI) to be imaged being part of an unrestrained live subject and having at least three spaced apart optical markers thereon. Simultaneous images are acquired from a first and a second camera of the markers from different angles. Motion data comprising 3D position and orientation of the markers relative to an initial reference position is then calculated. Motion corrected tomographic data obtained from the ROI using the motion data is then obtained, where motion corrected tomographic images obtained therefrom.

Label-free functional nucleic acid sensors for detecting target agents

DOEpatents

Lu, Yi; Xiang, Yu

2015-01-13

A general methodology to design label-free fluorescent functional nucleic acid sensors using a vacant site approach and an abasic site approach is described. In one example, a method for designing label-free fluorescent functional nucleic acid sensors (e.g., those that include a DNAzyme, aptamer or aptazyme) that have a tunable dynamic range through the introduction of an abasic site (e.g., dSpacer) or a vacant site into the functional nucleic acids. Also provided is a general method for designing label-free fluorescent aptamer sensors based on the regulation of malachite green (MG) fluorescence. A general method for designing label-free fluorescent catalytic and molecular beacons (CAMBs) is also provided. The methods demonstrated here can be used to design many other label-free fluorescent sensors to detect a wide range of analytes. Sensors and methods of using the disclosed sensors are also provided.

Optical tomographic memories: algorithms for the efficient information readout

NASA Astrophysics Data System (ADS)

Pantelic, Dejan V.

1990-07-01

Tomographic alogithms are modified in order to reconstruct the inf ormation previously stored by focusing laser radiation in a volume of photosensitive media. Apriori information about the position of bits of inf ormation is used. 1. THE PRINCIPLES OF TOMOGRAPHIC MEMORIES Tomographic principles can be used to store and reconstruct the inf ormation artificially stored in a bulk of a photosensitive media 1 The information is stored by changing some characteristics of a memory material (e. g. refractive index). Radiation from the two independent light sources (e. g. lasers) is f ocused inside the memory material. In this way the intensity of the light is above the threshold only in the localized point where the light rays intersect. By scanning the material the information can be stored in binary or nary format. When the information is stored it can be read by tomographic methods. However the situation is quite different from the classical tomographic problem. Here a lot of apriori information is present regarding the p0- sitions of the bits of information profile representing single bit and a mode of operation (binary or n-ary). 2. ALGORITHMS FOR THE READOUT OF THE TOMOGRAPHIC MEMORIES Apriori information enables efficient reconstruction of the memory contents. In this paper a few methods for the information readout together with the simulation results will be presented. Special attention will be given to the noise considerations. Two different

Initial experience with a nuclear medicine viewing workstation

NASA Astrophysics Data System (ADS)

Witt, Robert M.; Burt, Robert W.

1992-07-01

Graphical User Interfaced (GUI) workstations are now available from commercial vendors. We recently installed a GUI workstation in our nuclear medicine reading room for exclusive use of staff and resident physicians. The system is built upon a Macintosh platform and has been available as a DELTAmanager from MedImage and more recently as an ICON V from Siemens Medical Systems. The workstation provides only display functions and connects to our existing nuclear medicine imaging system via ethernet. The system has some processing capabilities to create oblique, sagittal and coronal views from transverse tomographic views. Hard copy output is via a screen save device and a thermal color printer. The DELTAmanager replaced a MicroDELTA workstation which had both process and view functions. The mouse activated GUI has made remarkable changes to physicians'' use of the nuclear medicine viewing system. Training time to view and review studies has been reduced from hours to about 30-minutes. Generation of oblique views and display of brain and heart tomographic studies has been reduced from about 30-minutes of technician''s time to about 5-minutes of physician''s time. Overall operator functionality has been increased so that resident physicians with little prior computer experience can access all images on the image server and display pertinent patient images when consulting with other staff.

Designing an anion-functionalized fluorescent ionic liquid as an efficient and reversible turn-off sensor for detecting SO2.

PubMed

Che, Siying; Dao, Rina; Zhang, Weidong; Lv, Xiaoyu; Li, Haoran; Wang, Congmin

2017-03-30

A novel anion-functionalized fluorescent ionic liquid was designed and prepared, which was capable of capturing sulphur dioxide with high capacity and could also be used as a good colorimetric and fluorescent SO 2 sensor. Compared to conventional fluorescent sensors, this fluorescent ionic liquid did not undergo aggregation-caused quenching or aggregation-induced emission, and the fluorescence was quenched when exposed to SO 2 , and the fluorescence would quench when exposed to SO 2 . The experimental absorption, spectroscopic investigation, and quantum chemical calculations indicated that the quenching of the fluorescence originated from SO 2 physical absorption, not chemical absorption. Furthermore, this fluorescent ionic liquid exhibited high selectivity, good quantification, and excellent reversibility for SO 2 detection, and showed potential for an excellent liquid sensor.

Watching stem cells at work with a flexible multiphoton tomograph

NASA Astrophysics Data System (ADS)

Uchugonova, Aisada; Hoffmann, Robert; Weinigel, Martin; König, Karsten

2012-03-01

There is a high demand for non-invasive imaging techniques that allow observation of stem cells in their native environment without significant input on cell metabolism, reproduction, and behavior. Easy accessible hair follicle pluripotent stem cells in the bulge area and dermal papilla are potential sources for stem cell based therapy. It has been shown that these cells are able to generate hair, non-follicle skin cells, nerves, vessels, smooth muscles etc. and may participate in wound healing processes. We report on the finding of nestin-GFP expressing stem cells in their native niche in the bulge of the hair follicle of living mice by using high-resolution in-vivo multiphoton tomography. The 3D imaging with submicron resolution was based on two-photon induced fluorescence and second harmonic generation (SHG) of collagen. Migrating stem cells from the bulge to their microenvironment have been detected inside the skin during optical deep tissue sectioning.

Nondestructive Evaluation of the J-2X Direct Metal Laser Sintered Gas Generator Discharge Duct

NASA Technical Reports Server (NTRS)

Esther, Elizabeth A.; Beshears, Ronald D.; Lash, Rhonda K.

2012-01-01

The J-2X program at NASA's Marshall Space Flight Center (MSFC) procured a direct metal laser sintered (DMLS) gas generator discharge duct from Pratt & Whitney Rocketdyne and Morris Technologies for a test program that would evaluate the material properties and durability of the duct in an engine-like environment. DMLS technology was pursued as a manufacturing alternative to traditional techniques, which used off nominal practices to manufacture the gas generator duct's 180 degree turn geometry. MSFC's Nondestructive Evaluation (NDE) Team performed radiographic, ultrasonic, computed tomographic, and fluorescent penetrant examinations of the duct. Results from the NDE examinations reveal some shallow porosity but no major defects in the as-manufactured material. NDE examinations were also performed after hot-fire testing the gas generator duct and yielded similar results pre and post-test and showed no flaw growth or development.

A Review of Imaging Techniques for Plant Phenotyping

PubMed Central

Li, Lei; Zhang, Qin; Huang, Danfeng

2014-01-01

Given the rapid development of plant genomic technologies, a lack of access to plant phenotyping capabilities limits our ability to dissect the genetics of quantitative traits. Effective, high-throughput phenotyping platforms have recently been developed to solve this problem. In high-throughput phenotyping platforms, a variety of imaging methodologies are being used to collect data for quantitative studies of complex traits related to the growth, yield and adaptation to biotic or abiotic stress (disease, insects, drought and salinity). These imaging techniques include visible imaging (machine vision), imaging spectroscopy (multispectral and hyperspectral remote sensing), thermal infrared imaging, fluorescence imaging, 3D imaging and tomographic imaging (MRT, PET and CT). This paper presents a brief review on these imaging techniques and their applications in plant phenotyping. The features used to apply these imaging techniques to plant phenotyping are described and discussed in this review. PMID:25347588

A novel fluorescent sensor for measurement of CFTR function by flow cytometry.

PubMed

Vijftigschild, Lodewijk A W; van der Ent, Cornelis K; Beekman, Jeffrey M

2013-06-01

Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene cause cystic fibrosis. CFTR-dependent iodide transport measured by fluorescent quenching of ectopically expressed halide-sensitive yellow fluorescent protein (YFP) is widely being used to study CFTR function by microscopy or plate readers. Since YFP fluorescence in these systems is dependent on YFP expression levels and iodide concentration, differences in sensor expression level between experimental units are normalized at the start of each experiment. To allow accurate measurement of CFTR function by flow cytometry, we reasoned that co-expression of an iodide insensitive fluorescent protein would allow for normalization of sensor expression levels and more accurate quantification of CFTR function. Our data indicated that dsRed and mKate fluorescence are iodide insensitive, and we determined an optimal format for co-expression of these fluorescent proteins with halide-sensitive YFP. We showed using microscopy that ratiometric measurement (YFP/mKate) corrects for differences in sensor expression levels. Ratiometric measurements were essential to accurately measure CFTR function by flow cytometry that we here describe for the first time. Mixing of wild type or mutant CFTR expressing cells indicated that addition of approximately 10% of wild type CFTR expressing cells could be distinguished by ratiometric YFP quenching. Flow cytometric ratiometric YFP quenching also allowed us to study CFTR mutants associated with differential residual function upon ectopic expression. Compared with conventional plate-bound CFTR function assays, the flow cytometric approach described here can be used to study CFTR function in suspension cells. It may be further adapted to study CFTR function in heterologous cell populations using cell surface markers and selection of cells that display high CFTR function by cell sorting. Copyright © 2013 International Society for Advancement of Cytometry.

[Speech syndrome and its course in patients who have sustained an ischemic stroke (clinico-tomographic study)].

PubMed

Stoliarova, L G; Varakin, Iu Ia; Vavilov, S B

1981-01-01

Clinical and tomographic examinations of 40 patients with aphasia developed after an ischemic stroke were carried out. In more than half of them no correlation between the aphasia gravity and character on the one hand, and the size and localization of the ischemic focus (or foci) in the brain on the other was noted. With similar character and gravity of the speech disorder the size and localization of the ischemic foci may be different, ad vice versa. It has been shown that the interrelations between the focal pathology of the brain and the character and gravity of speech disorders are very complicated. One should take into consideration the possibility of individual organization of the speech functions, the degree of the speech activity automatism before the disease, and the state of the cerebrovascular system as a whole.

Tomography of the Red Supergiant Star MU Cep

NASA Astrophysics Data System (ADS)

Kravchenko, Kateryna

2018-04-01

We present a tomographic method allowing to recover the velocity field at different optical depths in a stellar atmosphere. It is based on the computation of the contribution function to identify the depth of formation of spectral lines in order to construct numerical masks probing different optical depths. These masks are cross-correlated with observed spectra to extract information about the average shape of lines forming at a given optical depth and to derive the velocity field projected on the line of sight. We applied this method to series of spectra of the red supergiant star mu Cep and derived velocities in different atmospheric layers. The resulting velocity variations reveal complex atmospheric dynamics and indicate that convective cells are present in the atmosphere of the mu Cep. The mu Cep velocities were compared with those obtained by applying the tomographic masks to series of snapshot spectra from 3D radiative-hydrodynamics CO5BOLD simulations.

Image-guided therapies for myocardial repair: concepts and practical implementation

PubMed Central

Bengel, Frank M.; George, Richard T.; Schuleri, Karl H.; Lardo, Albert C.; Wollert, Kai C.

2013-01-01

Cell- and molecule-based therapeutic strategies to support wound healing and regeneration after myocardial infarction (MI) are under development. These emerging therapies aim at sustained preservation of ventricular function by enhancing tissue repair after myocardial ischaemia and reperfusion. Such therapies will benefit from guidance with regard to timing, regional targeting, suitable candidate selection, and effectiveness monitoring. Such guidance is effectively obtained by non-invasive tomographic imaging. Infarct size, tissue characteristics, muscle mass, and chamber geometry can be determined by magnetic resonance imaging and computed tomography. Radionuclide imaging can be used for the tracking of therapeutic agents and for the interrogation of molecular mechanisms such as inflammation, angiogenesis, and extracellular matrix activation. This review article portrays the hypothesis that an integrated approach with an early implementation of structural and molecular tomographic imaging in the development of novel therapies will provide a framework for achieving the goal of improved tissue repair after MI. PMID:23720377

Combining Spot Sign and Intracerebral Hemorrhage Score to Estimate Functional Outcome: Analysis From the PREDICT Cohort.

PubMed

Schneider, Hauke; Huynh, Thien J; Demchuk, Andrew M; Dowlatshahi, Dar; Rodriguez-Luna, David; Silva, Yolanda; Aviv, Richard; Dzialowski, Imanuel

2018-06-01

The intracerebral hemorrhage (ICH) score is the most commonly used grading scale for stratifying functional outcome in patients with acute ICH. We sought to determine whether a combination of the ICH score and the computed tomographic angiography spot sign may improve outcome prediction in the cohort of a prospective multicenter hemorrhage trial. Prospectively collected data from 241 patients from the observational PREDICT study (Prediction of Hematoma Growth and Outcome in Patients With Intracerebral Hemorrhage Using the CT-Angiography Spot Sign) were analyzed. Functional outcome at 3 months was dichotomized using the modified Rankin Scale (0-3 versus 4-6). Performance of (1) the ICH score and (2) the spot sign ICH score-a scoring scale combining ICH score and spot sign number-was tested. Multivariable analysis demonstrated that ICH score (odds ratio, 3.2; 95% confidence interval, 2.2-4.8) and spot sign number (n=1: odds ratio, 2.7; 95% confidence interval, 1.1-7.4; n>1: odds ratio, 3.8; 95% confidence interval, 1.2-17.1) were independently predictive of functional outcome at 3 months with similar odds ratios. Prediction of functional outcome was not significantly different using the spot sign ICH score compared with the ICH score alone (spot sign ICH score area under curve versus ICH score area under curve: P =0.14). In the PREDICT cohort, a prognostic score adding the computed tomographic angiography-based spot sign to the established ICH score did not improve functional outcome prediction compared with the ICH score. © 2018 American Heart Association, Inc.

Frequency Domain Fluorescent Molecular Tomography and Molecular Probes for Small Animal Imaging

NASA Astrophysics Data System (ADS)

Kujala, Naresh Gandhi

Fluorescent molecular tomography (FMT) is a noninvasive biomedical optical imaging that enables 3-dimensional quantitative determination of fluorochromes distributed in biological tissues. There are three methods for imaging large volume tissues based on different light sources: (a) using a light source of constant intensity, through a continuous or constant wave, (b) using a light source that is intensity modulated with a radio frequency (RF), and (c) using ultrafast pulses in the femtosecond range. In this study, we have developed a frequency domain fluorescent molecular tomographic system based on the heterodyne technique, using a single source and detector pair that can be used for small animal imaging. In our system, the intensity of the laser source is modulated with a RF frequency to produce a diffuse photon density wave in the tissue. The phase of the diffuse photon density wave is measured by comparing the reference signal with the signal from the tissue using a phasemeter. The data acquisition was performed by using a Labview program. The results suggest that we can measure the phase change from the heterogeneous inside tissue. Combined with fiber optics and filter sets, the system can be used to sensitively image the targeted fluorescent molecular probes, allowing the detection of cancer at an early stage. We used the system to detect the tumor-targeting molecular probe Alexa Fluor 680 and Alexa Fluor 750 bombesin peptide conjugates in phantoms as well as mouse tissues. We also developed and evaluated fluorescent Bombesin (BBN) probes to target gastrin-releasing peptide (GRP) receptors for optical molecular imaging. GRP receptors are over-expressed in several types of human cancer cells, including breast, prostate, small cell lung, and pancreatic cancers. BBN is a 14 amino acid peptide that is an analogue to human gastrin-releasing peptide that binds specifically to GRPr receptors. BBN conjugates are significant in cancer detection and therapy. The optical molecular probe AF750 BBN peptide exhibits optimal pharmacokinetic properties for targeting GRPr in mice. Fluorescent microscopic imaging of the molecular probe in PC-3 prostate and T-47D breast cancer cell lines indicated specific uptake, internalization, and receptor blocking of these probes. In vivo investigations in severely compromised immunodeficient (SCID) mice bearing xenografted PC-3 prostate and T47-D breast cancer lesions demonstrated the ability of this new molecular probe to specifically target tumor tissue with high selectively and affinity.

Improved axial point spread function in a two-frequency laser scanning confocal fluorescence microscope

NASA Astrophysics Data System (ADS)

Wu, Jheng-Syong; Chung, Yung-Chin; Chien, Jun-Jei; Chou, Chien

2018-01-01

A two-frequency laser scanning confocal fluorescence microscope (TF-LSCFM) based on intensity modulated fluorescence signal detection was proposed. The specimen-induced spherical aberration and scattering effect were suppressed intrinsically, and high image contrast was presented due to heterodyne interference. An improved axial point spread function in a TF-LSCFM compared with a conventional laser scanning confocal fluorescence microscope was demonstrated and discussed.

Tomographic imaging of the shallow crustal structure of the East Pacific Rise at 9 deg 30 min N

NASA Astrophysics Data System (ADS)

Toomey, Douglas R.; Solomon, Sean C.; Purdy, G. M.

1994-12-01

Compressional wave travel times from a seismic tomography experiment at 9 deg 30 min N on the East Pacific Rise are analyzed by a new tomographic method to determine the three-dimensional seismic velocity structure of the upper 2.5 km of oceanic crust within a 20 x 18 km area centered on the rise axis. The data comprise the travel times and associated uncertainties of 1459 compressional waves that have propagated above the axial magma chamber. A careful analysis of source and receiver parameters, in conjunction with an automated method of picking P wave onsets and assigning uncertainties, constrains the prior uncertainty in the data to 5 to 20 ms. The new tomographic method employs graph theory to estimate ray paths and travel times through strongly heterogeneous and densely parameterized seismic velocity models. The nonlinear inverse method uses a jumping strategy to minimize a functional that includes the penalty function, horizontal and vertical smoothing constraints, and prior model assumptions; all constraints applied to model perturbations are normalized to remove bias. We use the tomographic method to reject the null hypothesis that the axial seismic structure is two-dimensional. Three-dimensional models reveal a seismic structure that correlates well with cross- and along-axis variations in seafloor morphology, the location of the axial summit caldera, and the distribution of seafloor hydrothermal activity. The along-axis segmentation of the seismic structure above the axial magma chamber is consistent with the hypothesis that mantle-derived melt is preferentially injected midway along a locally linear segment of the rise and that the architecture of the crustal section is characterized by an en echelon series of elongate axial volcanoes approximately 10 km in length. The seismic data are compatible with a 300- to 500-m-thick thermal anomaly above a midcrustal melt lens; such an interpretation suggests that hydrothermal fluids may not have penetrated this region in the last 10(exp 3) years. Asymmetries in the seismic structure across the rise support the inferences that the thickness of seismic layer 2 and the average midcrustal temperature increase to the west of the rise axis. These anomalies may be the result of off-axis magmatism; alternatively, the asymmetric thermal anomaly may be the consequence of differences in the depth extent of hydrothermal cooling.

Can macrocirculation changes predict nonhealing diabetic foot ulcers?

PubMed

Lee, Ye-Na; Kim, Hyon-Surk; Kang, Jeong-A; Han, Seung-Kyu

2014-01-01

Transcutaneous partial oxygen tension (TcpO2) is considered the gold standard for assessment of tissue oxygenation, which is an essential factor for wound healing. The purpose of this study was to evaluate the association between macrocirculation and TcpO2 in persons with diabetes mellitus. Ninety-eight patients with diabetic foot ulcers participated in the study (61 men and 37 women). The subjects had a mean age of 66.6 years (range, 30-83 years) and were treated at the Diabetic Wound Center of Korea University Guro Hospital, Seoul, Republic of Korea. Macrocirculation was evaluated using 2 techniques: computed tomographic angiography and Doppler ultrasound. Macrocirculation scores were based on the patency of the two tibial arteries in 98 patients. Computed tomographic angiography and Doppler ultrasound scores (0-4 points) were given according to intraluminal filling defects and arterial pulse waveform of each vessel, respectively. Tissue oxygenation was measured by TcpO2. Macrocirculation scores were statistically analyzed as a function of the TcpO2. Statistical analysis revealed no significant linear trend between the macrocirculation status and TcpO2. Biavariate analysis using the Fisher exact test, Mantel-Haenszel tests, and McNemar-Bowker tests also found no significant relationship between macrocirculation and TcpO2. Computed tomographic angiography and Doppler ultrasound are not sufficiently reliable substitutes for TcpO2 measurements in regard to determining the optimal treatment for diabetic patients.

Representation of photon limited data in emission tomography using origin ensembles

NASA Astrophysics Data System (ADS)

Sitek, A.

2008-06-01

Representation and reconstruction of data obtained by emission tomography scanners are challenging due to high noise levels in the data. Typically, images obtained using tomographic measurements are represented using grids. In this work, we define images as sets of origins of events detected during tomographic measurements; we call these origin ensembles (OEs). A state in the ensemble is characterized by a vector of 3N parameters Y, where the parameters are the coordinates of origins of detected events in a three-dimensional space and N is the number of detected events. The 3N-dimensional probability density function (PDF) for that ensemble is derived, and we present an algorithm for OE image estimation from tomographic measurements. A displayable image (e.g. grid based image) is derived from the OE formulation by calculating ensemble expectations based on the PDF using the Markov chain Monte Carlo method. The approach was applied to computer-simulated 3D list-mode positron emission tomography data. The reconstruction errors for a 10 000 000 event acquisition for simulated ranged from 0.1 to 34.8%, depending on object size and sampling density. The method was also applied to experimental data and the results of the OE method were consistent with those obtained by a standard maximum-likelihood approach. The method is a new approach to representation and reconstruction of data obtained by photon-limited emission tomography measurements.

Quantification of endocytosis using a folate functionalized silica hollow nanoshell platform

PubMed Central

Sandoval, Sergio; Mendez, Natalie; Alfaro, Jesus G.; Yang, Jian; Aschemeyer, Sharraya; Liberman, Alex; Trogler, William C.; Kummel, Andrew C.

2015-01-01

Abstract. A quantification method to measure endocytosis was designed to assess cellular uptake and specificity of a targeting nanoparticle platform. A simple N-hydroxysuccinimide ester conjugation technique to functionalize 100-nm hollow silica nanoshell particles with fluorescent reporter fluorescein isothiocyanate and folate or polyethylene glycol (PEG) was developed. Functionalized nanoshells were characterized using scanning electron microscopy and transmission electron microscopy and the maximum amount of folate functionalized on nanoshell surfaces was quantified with UV-Vis spectroscopy. The extent of endocytosis by HeLa cervical cancer cells and human foreskin fibroblast (HFF-1) cells was investigated in vitro using fluorescence and confocal microscopy. A simple fluorescence ratio analysis was developed to quantify endocytosis versus surface adhesion. Nanoshells functionalized with folate showed enhanced endocytosis by cancer cells when compared to PEG functionalized nanoshells. Fluorescence ratio analyses showed that 95% of folate functionalized silica nanoshells which adhered to cancer cells were endocytosed, while only 27% of PEG functionalized nanoshells adhered to the cell surface and underwent endocytosis when functionalized with 200 and 900  μg, respectively. Additionally, the endocytosis of folate functionalized nanoshells proved to be cancer cell selective while sparing normal cells. The developed fluorescence ratio analysis is a simple and rapid verification/validation method to quantify cellular uptake between datasets by using an internal control for normalization. PMID:26315280

First results from the ionospheric tomography experiment using beacon TEC data obtained by means of a network along a longitude of 136°E over Japan

NASA Astrophysics Data System (ADS)

Thampi, Smitha V.; Yamamoto, Mamoru

2010-03-01

A chain of newly designed GNU (GNU is not UNIX) Radio Beacon Receivers (GRBR) has recently been established over Japan, primarily for tomographic imaging of the ionosphere over this region. Receivers installed at Shionomisaki (33.45°N, 135.8°E), Shigaraki (34.8°N, 136.1°E), and Fukui (36°N, 136°E) continuously track low earth orbiting satellites (LEOS), mainly OSCAR, Cosmos, and FORMOSAT-3/COSMIC, to obtain simultaneous total electron content (TEC) data from these three locations, which are then used for the tomographic reconstruction of ionospheric electron densities. This is the first GRBR network established for TEC observations, and the first beacon-based tomographic imaging in Japanese longitudes. The first tomographic images revealed the temporal evolution with all of the major features in the ionospheric electron density distribution over Japan. A comparison of the tomographically reconstructed electron densities with the ƒ o F 2 data from Kokubunji (35°N, 139°E) revealed that there was good agreement between the datasets. These first results show the potential of GRBR and its network for making continuous, unattended ionospheric TEC measurements and for tomographic imaging of the ionosphere.

A new fluorescent dye accumulation assay for parallel measurements of the ABCG2, ABCB1 and ABCC1 multidrug transporter functions.

PubMed

Szabó, Edit; Türk, Dóra; Telbisz, Ágnes; Kucsma, Nóra; Horváth, Tamás; Szakács, Gergely; Homolya, László; Sarkadi, Balázs; Várady, György

2018-01-01

ABC multidrug transporters are key players in cancer multidrug resistance and in general xenobiotic elimination, thus their functional assays provide important tools for research and diagnostic applications. In this study we have examined the potential interactions of three key human ABC multidrug transporters with PhenGreen diacetate (PGD), a cell permeable fluorescent metal ion indicator. The non-fluorescent, hydrophobic PGD rapidly enters the cells and, after cleavage by cellular esterases, in the absence of quenching metal ions, PhenGreen (PG) becomes highly fluorescent. We found that in cells expressing functional ABCG2, ABCB1, or ABCC1 transporters, cellular PG fluorescence is strongly reduced. This fluorescence signal in the presence of specific transporter inhibitors is increased to the fluorescence levels in the control cells. Thus the PG accumulation assay is a new, unique tool for the parallel determination of the function of the ABCG2, ABCB1, and ABCC1 multidrug transporters. Since PG has very low cellular toxicity, the PG accumulation assay also allows the selection, separation and culturing of selected cell populations expressing either of these transporters.

On the feasibility of tomographic-PIV with low pulse energy illumination in a lifted turbulent jet flame

NASA Astrophysics Data System (ADS)

Boxx, I.; Carter, C. D.; Meier, W.

2014-08-01

Tomographic particle image velocimetry (tomographic-PIV) is a recently developed measurement technique used to acquire volumetric velocity field data in liquid and gaseous flows. The technique relies on line-of-sight reconstruction of the rays between a 3D particle distribution and a multi-camera imaging system. In a turbulent flame, however, index-of-refraction variations resulting from local heat-release may inhibit reconstruction and thereby render the technique infeasible. The objective of this study was to test the efficacy of tomographic-PIV in a turbulent flame. An additional goal was to determine the feasibility of acquiring usable tomographic-PIV measurements in a turbulent flame at multi-kHz acquisition rates with current-generation laser and camera technology. To this end, a setup consisting of four complementary metal oxide semiconductor cameras and a dual-cavity Nd:YAG laser was implemented to test the technique in a lifted turbulent jet flame. While the cameras were capable of kHz-rate image acquisition, the laser operated at a pulse repetition rate of only 10 Hz. However, use of this laser allowed exploration of the required pulse energy and thus power for a kHz-rate system. The imaged region was 29 × 28 × 2.7 mm in size. The tomographic reconstruction of the 3D particle distributions was accomplished using the multiplicative algebraic reconstruction technique. The results indicate that volumetric velocimetry via tomographic-PIV is feasible with pulse energies of 25 mJ, which is within the capability of current-generation kHz-rate diode-pumped solid-state lasers.

Large-scale tomographic particle image velocimetry using helium-filled soap bubbles

NASA Astrophysics Data System (ADS)

Kühn, Matthias; Ehrenfried, Klaus; Bosbach, Johannes; Wagner, Claus

2011-04-01

To measure large-scale flow structures in air, a tomographic particle image velocimetry (tomographic PIV) system for measurement volumes of the order of one cubic metre is developed, which employs helium-filled soap bubbles (HFSBs) as tracer particles. The technique has several specific characteristics compared to most conventional tomographic PIV systems, which are usually applied to small measurement volumes. One of them is spot lights on the HFSB tracers, which slightly change their position, when the direction of observation is altered. Further issues are the large particle to voxel ratio and the short focal length of the used camera lenses, which result in a noticeable variation of the magnification factor in volume depth direction. Taking the specific characteristics of the HFSBs into account, the feasibility of our large-scale tomographic PIV system is demonstrated by showing that the calibration errors can be reduced down to 0.1 pixels as required. Further, an accurate and fast implementation of the multiplicative algebraic reconstruction technique, which calculates the weighting coefficients when needed instead of storing them, is discussed. The tomographic PIV system is applied to measure forced convection in a convection cell at a Reynolds number of 530 based on the inlet channel height and the mean inlet velocity. The size of the measurement volume and the interrogation volumes amount to 750 mm × 450 mm × 165 mm and 48 mm × 48 mm × 24 mm, respectively. Validation of the tomographic PIV technique employing HFSBs is further provided by comparing profiles of the mean velocity and of the root mean square velocity fluctuations to respective planar PIV data.

Clinical, radiographic, ultrasonographic and computed tomographic features of nonseptic osteitis of the axial border of the proximal sesamoid bones.

PubMed

Vanderperren, K; Bergman, H J; Spoormakers, T J P; Pille, F; Duchateau, L; Puchalski, S M; Saunders, J H

2014-07-01

Lysis of the axial aspect of equine proximal sesamoid bones (PSBs) is a rare condition reported to have septic or traumatic origins. Limited information exists regarding imaging of nonseptic axial osteitis of a PSB. To report the clinical, radiographic, ultrasonographic, computed tomographic and intra-arterial contrast-enhanced computed tomographic abnormalities in horses with axial nonseptic osteitis of a PSB. Retrospective clinical study. Eighteen horses diagnosed with nonseptic osteitis of the axial border of a PSB between 2007 and 2012 were reviewed retrospectively. Case details, clinical examination, radiographic, ultrasonographic, computed tomographic and intra-arterial/intra-articular contrast-enhanced computed tomographic features were recorded, when available. Radiographic, ultrasonographic and computed tomographic evaluations of the fetlock region had been performed on 18, 15 and 9 horses, respectively. The effect of the degree of lysis on the grade and duration of lameness was determined. All horses had chronic unilateral lameness, 4 with forelimb and 14 with hindlimb signs. On radiographs, lysis was identified in both PSBs in 14 horses, one PSB in 3 horses and in one horse no lysis was identified. The degree of osteolysis was variable. Ultrasonography identified variably sized irregularities of the bone surface and alteration in echogenicity of the palmar/plantar ligament (PL). All horses undergoing computed tomographic examination (n = 9) had biaxial lysis. The lesions were significantly longer and deeper on computed tomographic images compared with radiographic images. Intra-arterial contrast-enhanced computed tomography may reveal moderate to marked contrast enhancement of the PL. There was no significant effect of the degree of lysis on the grade and duration of lameness. Lesions of nonseptic axial osteitis of a PSB can be identified using a combination of radiography and ultrasonography. Computed tomography provides additional information regarding the extent of the pathology. © 2013 EVJ Ltd.

Fluorescent proteins function as a prey attractant: experimental evidence from the hydromedusa Olindias formosus and other marine organisms

PubMed Central

Haddock, Steven H. D.; Dunn, Casey W.

2015-01-01

ABSTRACT Although proteins in the green fluorescent protein family (GFPs) have been discovered in a wide array of taxa, their ecological functions in these organisms remain unclear. Many hypothesized roles are related to modifying bioluminescence spectra or modulating the light regime for algal symbionts, but these do not explain the presence of GFPs in animals that are non-luminous and non-symbiotic. Other hypothesized functions are unrelated to the visual signals themselves, including stress responses and antioxidant roles, but these cannot explain the localization of fluorescence in particular structures on the animals. Here we tested the hypothesis that fluorescence might serve to attract prey. In laboratory experiments, the predator was the hydromedusa Olindias formosus (previously known as O. formosa), which has fluorescent and pigmented patches on the tips of its tentacles. The prey, juvenile rockfishes in the genus Sebastes, were significantly more attracted (P<1×10−5) to the medusa's tentacles under lighting conditions where fluorescence was excited and tentacle tips were visible above the background. The fish did not respond significantly when treatments did not include fluorescent structures or took place under yellow or white lights, which did not generate fluorescence visible above the ambient light. Furthermore, underwater observations of the behavior of fishes when presented with a brightly illuminated point showed a strong attraction to this visual stimulus. In situ observations also provided evidence for fluorescent lures as supernormal stimuli in several other marine animals, including the siphonophore Rhizophysa eysenhardti. Our results support the idea that fluorescent structures can serve as prey attractants, thus providing a potential function for GFPs and other fluorescent proteins in a diverse range of organisms. PMID:26231627

Effect of Surface Chemistry on the Fluorescence of Detonation Nanodiamonds.

PubMed

Reineck, Philipp; Lau, Desmond W M; Wilson, Emma R; Fox, Kate; Field, Matthew R; Deeleepojananan, Cholaphan; Mochalin, Vadym N; Gibson, Brant C

2017-11-28

Detonation nanodiamonds (DNDs) have unique physical and chemical properties that make them invaluable in many applications. However, DNDs are generally assumed to show weak fluorescence, if any, unless chemically modified with organic molecules. We demonstrate that detonation nanodiamonds exhibit significant and excitation-wavelength-dependent fluorescence from the visible to the near-infrared spectral region above 800 nm, even without the engraftment of organic molecules to their surfaces. We show that this fluorescence depends on the surface functionality of the DND particles. The investigated functionalized DNDs, produced from the same purified DND as well as the as-received polyfunctional starting material, are hydrogen, hydroxyl, carboxyl, ethylenediamine, and octadecylamine-terminated. All DNDs are investigated in solution and on a silicon wafer substrate and compared to fluorescent high-pressure high-temperature nanodiamonds. The brightest fluorescence is observed from octadecylamine-functionalized particles and is more than 100 times brighter than the least fluorescent particles, carboxylated DNDs. The majority of photons emitted by all particle types likely originates from non-diamond carbon. However, we locally find bright and photostable fluorescence from nitrogen-vacancy centers in diamond in hydrogenated, hydroxylated, and carboxylated detonation nanodiamonds. Our results contribute to understanding the effects of surface chemistry on the fluorescence of DNDs and enable the exploration of the fluorescent properties of DNDs for applications in theranostics as nontoxic fluorescent labels, sensors, nanoscale tracers, and many others where chemically stable and brightly fluorescent nanoparticles with tailorable surface chemistry are needed.

Three-dimensional fluorescence-enhanced optical tomography using a hand-held probe based imaging system

PubMed Central

Ge, Jiajia; Zhu, Banghe; Regalado, Steven; Godavarty, Anuradha

2008-01-01

Hand-held based optical imaging systems are a recent development towards diagnostic imaging of breast cancer. To date, all the hand-held based optical imagers are used to perform only surface mapping and target localization, but are not capable of demonstrating tomographic imaging. Herein, a novel hand-held probe based optical imager is developed towards three-dimensional (3-D) optical tomography studies. The unique features of this optical imager, which primarily consists of a hand-held probe and an intensified charge coupled device detector, are its ability to; (i) image large tissue areas (5×10 sq. cm) in a single scan, (ii) perform simultaneous multiple point illumination and collection, thus reducing the overall imaging time; and (iii) adapt to varying tissue curvatures, from a flexible probe head design. Experimental studies are performed in the frequency domain on large slab phantoms (∼650 ml) using fluorescence target(s) under perfect uptake (1:0) contrast ratios, and varying target depths (1–2 cm) and X-Y locations. The effect of implementing simultaneous over sequential multiple point illumination towards 3-D tomography is experimentally demonstrated. The feasibility of 3-D optical tomography studies has been demonstrated for the first time using a hand-held based optical imager. Preliminary fluorescence-enhanced optical tomography studies are able to reconstruct 0.45 ml target(s) located at different target depths (1–2 cm). However, the depth recovery was limited as the actual target depth increased, since only reflectance measurements were acquired. Extensive tomography studies are currently carried out to determine the resolution and performance limits of the imager on flat and curved phantoms. PMID:18697559

A fluorogenic near-infrared imaging agent for quantifying plasma and local tissue renin activity in vivo and ex vivo

PubMed Central

Zhang, Jun; Preda, Dorin V.; Vasquez, Kristine O.; Morin, Jeff; Delaney, Jeannine; Bao, Bagna; Percival, M. David; Xu, Daigen; McKay, Dan; Klimas, Michael; Bednar, Bohumil; Sur, Cyrille; Gao, David Z.; Madden, Karen; Yared, Wael; Rajopadhye, Milind

2012-01-01

The renin-angiotensin system (RAS) is well studied for its regulation of blood pressure and fluid homeostasis, as well as for increased activity associated with a variety of diseases and conditions, including cardiovascular disease, diabetes, and kidney disease. The enzyme renin cleaves angiotensinogen to form angiotensin I (ANG I), which is further cleaved by angiotensin-converting enzyme to produce ANG II. Although ANG II is the main effector molecule of the RAS, renin is the rate-limiting enzyme, thus playing a pivotal role in regulating RAS activity in hypertension and organ injury processes. Our objective was to develop a near-infrared fluorescent (NIRF) renin-imaging agent for noninvasive in vivo detection of renin activity as a measure of tissue RAS and in vitro plasma renin activity. We synthesized a renin-activatable agent, ReninSense 680 FAST (ReninSense), using a NIRF-quenched substrate derived from angiotensinogen that is cleaved specifically by purified mouse and rat renin enzymes to generate a fluorescent signal. This agent was assessed in vitro, in vivo, and ex vivo to detect and quantify increases in plasma and kidney renin activity in sodium-sensitive inbred C57BL/6 mice maintained on a low dietary sodium and diuretic regimen. Noninvasive in vivo fluorescence molecular tomographic imaging of the ReninSense signal in the kidney detected increased renin activity in the kidneys of hyperreninemic C57BL/6 mice. The agent also effectively detected renin activity in ex vivo kidneys, kidney tissue sections, and plasma samples. This approach could provide a new tool for assessing disorders linked to altered tissue and plasma renin activity and to monitor the efficacy of therapeutic treatments. PMID:22674025

Three-dimensional fluorescence-enhanced optical tomography using a hand-held probe based imaging system.

PubMed

Ge, Jiajia; Zhu, Banghe; Regalado, Steven; Godavarty, Anuradha

2008-07-01

Hand-held based optical imaging systems are a recent development towards diagnostic imaging of breast cancer. To date, all the hand-held based optical imagers are used to perform only surface mapping and target localization, but are not capable of demonstrating tomographic imaging. Herein, a novel hand-held probe based optical imager is developed towards three-dimensional (3-D) optical tomography studies. The unique features of this optical imager, which primarily consists of a hand-held probe and an intensified charge coupled device detector, are its ability to; (i) image large tissue areas (5 x 10 sq. cm) in a single scan, (ii) perform simultaneous multiple point illumination and collection, thus reducing the overall imaging time; and (iii) adapt to varying tissue curvatures, from a flexible probe head design. Experimental studies are performed in the frequency domain on large slab phantoms (approximately 650 ml) using fluorescence target(s) under perfect uptake (1:0) contrast ratios, and varying target depths (1-2 cm) and X-Y locations. The effect of implementing simultaneous over sequential multiple point illumination towards 3-D tomography is experimentally demonstrated. The feasibility of 3-D optical tomography studies has been demonstrated for the first time using a hand-held based optical imager. Preliminary fluorescence-enhanced optical tomography studies are able to reconstruct 0.45 ml target(s) located at different target depths (1-2 cm). However, the depth recovery was limited as the actual target depth increased, since only reflectance measurements were acquired. Extensive tomography studies are currently carried out to determine the resolution and performance limits of the imager on flat and curved phantoms.

SIRT-FILTER v1.0.0

DOE Office of Scientific and Technical Information (OSTI.GOV)

PELT, DANIEL

2017-04-21

Small Python package to compute tomographic reconstructions using a reconstruction method published in: Pelt, D.M., & De Andrade, V. (2017). Improved tomographic reconstruction of large-scale real-world data by filter optimization. Advanced Structural and Chemical Imaging 2: 17; and Pelt, D. M., & Batenburg, K. J. (2015). Accurately approximating algebraic tomographic reconstruction by filtered backprojection. In Proceedings of The 13th International Meeting on Fully Three-Dimensional Image Reconstruction in Radiology and Nuclear Medicine (pp. 158-161).

Evidence for the contemporary magmatic system beneath Long Valley Caldera from local earthquake tomography and receiver function analysis

USGS Publications Warehouse

Seccia, D.; Chiarabba, C.; De Gori, P.; Bianchi, I.; Hill, D.P.

2011-01-01

We present a new P wave and S wave velocity model for the upper crust beneath Long Valley Caldera obtained using local earthquake tomography and receiver function analysis. We computed the tomographic model using both a graded inversion scheme and a traditional approach. We complement the tomographic I/P model with a teleseismic receiver function model based on data from broadband seismic stations (MLAC and MKV) located on the SE and SW margins of the resurgent dome inside the caldera. The inversions resolve (1) a shallow, high-velocity P wave anomaly associated with the structural uplift of a resurgent dome; (2) an elongated, WNW striking low-velocity anomaly (8%–10 % reduction in I/P) at a depth of 6 km (4 km below mean sea level) beneath the southern section of the resurgent dome; and (3) a broad, low-velocity volume (–5% reduction in I/P and as much as 40% reduction in I/S) in the depth interval 8–14 km (6–12 km below mean sea level) beneath the central section of the caldera. The two low-velocity volumes partially overlap the geodetically inferred inflation sources that drove uplift of the resurgent dome associated with caldera unrest between 1980 and 2000, and they likely reflect the ascent path for magma or magmatic fluids into the upper crust beneath the caldera.

Clinical applications with the HIDAC positron camera

NASA Astrophysics Data System (ADS)

Frey, P.; Schaller, G.; Christin, A.; Townsend, D.; Tochon-Danguy, H.; Wensveen, M.; Donath, A.

1988-06-01

A high density avalanche chamber (HIDAC) positron camera has been used for positron emission tomographic (PET) imaging in three different human studies, including patients presenting with: (I) thyroid diseases (124 cases); (II) clinically suspected malignant tumours of the pharynx or larynx (ENT) region (23 cases); and (III) clinically suspected primary malignant and metastatic tumours of the liver (9 cases, 19 PET scans). The positron emitting radiopharmaceuticals used for the three studies were Na 124I (4.2 d half-life) for the thyroid, 55Co-bleomycin (17.5 h half-life) for the ENT-region and 68Ga-colloid (68 min half-life) for the liver. Tomographic imaging was performed: (I) 24 h after oral Na 124I administration to the thyroid patients, (II) 18 h after intraveneous administration of 55Co-bleomycin to the ENT patients and (III) 20 min following the intraveneous injection of 68Ga-colloid to the liver tumour patients. Three different imaging protocols were used with the HIDAC positron camera to perform appropriate tomographic imaging in each patient study. Promising results were obtained in all three studies, particularly in tomographic thyroid imaging, where a significant clinical contribution is made possible for diagnosis and therapy planning by the PET technique. In the other two PET studies encouraging results were obtained for the detection and precise localisation of malignant tumour disease including an estimate of the functional liver volume based on the reticulo-endothelial-system (RES) of the liver, obtained in vivo, and the three-dimensional display of liver PET data using shaded graphics techniques. The clinical significance of the overall results obtained in both the ENT and the liver PET study, however, is still uncertain and the respective role of PET as a new imaging modality in these applications is not yet clearly established. To appreciate the clinical impact made by PET in liver and ENT malignant tumour staging needs further investigation, and more detailed data on a larger number of clinical and experimental PET scans will be necessary for definitive evaluation. Nevertheless, the HIDAC positron camera may be used for clinical PET imaging in well-defined patient cases, particularly in situations where both high spatial resolution is desired in the reconstructed image of the examined pathological condition and at the same time "static" PET imaging may be adequate, as is the case in thyroid-, ENT- and liver tomographic imaging using the HIDAC positron camera.

A review of US anthropometric reference data (1971 2000) with comparisons to both stylized and tomographic anatomic models

NASA Astrophysics Data System (ADS)

Huh, C.; Bolch, W. E.

2003-10-01

Two classes of anatomic models currently exist for use in both radiation protection and radiation dose reconstruction: stylized mathematical models and tomographic voxel models. The former utilize 3D surface equations to represent internal organ structure and external body shape, while the latter are based on segmented CT or MR images of a single individual. While tomographic models are clearly more anthropomorphic than stylized models, a given model's characterization as being anthropometric is dependent upon the reference human to which the model is compared. In the present study, data on total body mass, standing/sitting heights and body mass index are collected and reviewed for the US population covering the time interval from 1971 to 2000. These same anthropometric parameters are then assembled for the ORNL series of stylized models, the GSF series of tomographic models (Golem, Helga, Donna, etc), the adult male Zubal tomographic model and the UF newborn tomographic model. The stylized ORNL models of the adult male and female are found to be fairly representative of present-day average US males and females, respectively, in terms of both standing and sitting heights for ages between 20 and 60-80 years. While the ORNL adult male model provides a reasonably close match to the total body mass of the average US 21-year-old male (within ~5%), present-day 40-year-old males have an average total body mass that is ~16% higher. For radiation protection purposes, the use of the larger 73.7 kg adult ORNL stylized hermaphrodite model provides a much closer representation of average present-day US females at ages ranging from 20 to 70 years. In terms of the adult tomographic models from the GSF series, only Donna (40-year-old F) closely matches her age-matched US counterpart in terms of average body mass. Regarding standing heights, the better matches to US age-correlated averages belong to Irene (32-year-old F) for the females and Golem (38-year-old M) for the males. Both Helga (27-year-old F) and Donna, however, provide good matches to average US sitting heights for adult females, while Golem and Otoko (male of unknown age) yield sitting heights that are slightly below US adult male averages. Finally, Helga is seen as the only GSF tomographic female model that yields a body mass index in line with her average US female counterpart at age 26. In terms of dose reconstruction activities, however, all current tomographic voxel models are valuable assets in attempting to cover the broad distribution of individual anthropometric parameters representative of the current US population. It is highly recommended that similar attempts to create a broad library of tomographic models be initiated in the United States and elsewhere to complement and extend the limited number of tomographic models presently available for these efforts.

In Vivo Kinetics of Mesenchymal Stem Cells Transplanted into the Knee Joint in a Rat Model Using a Novel Magnetic Method of Localization.

PubMed

Ikuta, Yasunari; Kamei, Naosuke; Ishikawa, Masakazu; Adachi, Nobuo; Ochi, Mitsuo

2015-10-01

We have developed a magnetic system for targeting cells in minimally invasive cell transplantation. Magnetically labeled MSCs (m-MSCs) with nanoscale iron particles can be guided into the desired region by magnetic force from an extracorporeal device. We reported that magnetic targeting of m-MSCs enhances cartilage repair in a mini-pig model. However, the detailed kinetics of these magnetically targeted m-MSCs remain unknown. For clinical use, this aspect should be clarified from a safety standpoint. We therefore investigated the spatial and temporal distribution of the fluorescently-labeled m-MSCs transplanted into the knee joint using in vivo fluorescence combined with three-dimensional computed tomographic imaging in a rat model. Although the intraarticularly injected m-MSCs were spread throughout the joint cavity in the absence of magnetic force, the magnetic force caused the injected m-MSCs to accumulate around the chondral lesion. Further examinations including ex vivo imaging, histological assessments and reverse transcription polymerase chain reaction revealed that transplanted MSCs were not present in any major organs after intraarticular administration, regardless of magnetic targeting. Our data suggest that m-MSCs can be accumulated efficiently into a chondral lesion using our magnetic targeting system, while none of the intraarticularly transplanted MSCs migrate to other major organs. © 2015 Wiley Periodicals, Inc.

Development of an endoscopic fluorescence image-guided OCT probe for oral cancer detection

NASA Astrophysics Data System (ADS)

McNichols, Roger J.; Gowda, Ashok; Bell, Brent A.; Johnigan, Richard M.; Calhoun, Karen H.; Motamedi, Massoud

2001-06-01

Oral squamous cell carcinoma is a disease which progresses through a number of well-defined morphological and biochemical changes. Optical coherence tomography (OCT) is a rapidly-evolving, non-invasive imaging modality which allows detailed probing of subsurface tissue structures with resolution on the order of microns. While this technique offers tremendous potential as a diagnostic tool for detection and characterization of oral cancer, OCT imaging is presently associated with a field of view on the order of millimeters, and acquisition time on the order of seconds. Thus, OCT's utility as a rapid cancer screening technique is presently limited. On the other hand, imaging of tissue autofluorescence provides a very rapid, high-throughput method for cancer screening. However, while autofluorescence measures may be sensitive to cancer, they are often non- specific and lead to a large number of false positives. In the present work, we have developed a fluorescence image guided optical coherence tomographic (FIG-OCT) probe in which tissue autofluorescence images are simultaneously used to guide OCT image acquisition of suspicious regions in real time. We have begun pre-clinical pilot studies with this instrument in a DMBA-induced model of oral cancer in the hamster cheek pouch. Initial results indicate that the FIG- OCT approach shows promise as a rapid and effective tool for screening of oral cancer.

Intravenous volume tomographic pulmonary angiography imaging

NASA Astrophysics Data System (ADS)

Ning, Ruola; Strang, John G.; Chen, Biao; Conover, David L.; Yu, Rongfeng

1999-05-01

This study presents a new intravenous (IV) tomographic angiography imaging technique, called intravenous volume tomographic digital angiography (VTDA) for cross sectional pulmonary angiography. While the advantages of IV-VTDA over spiral CT in terms of volume scanning time and resolution have been validated and reported in our previous papers for head and neck vascular imaging, the superiority of IV-VTDA over spiral CT for cross sectional pulmonary angiography has not been explored yet. The purpose of this study is to demonstrate the advantage of isotropic resolution of IV-VTDA in the x, y and z directions through phantom and animal studies, and to explore its clinical application for detecting clots in pulmonary angiography. A prototype image intensifier-based VTDA imaging system has been designed and constructed by modifying a GE 8800 CT scanner. This system was used for a series of phantom and dog studies. A pulmonary vascular phantom was designed and constructed. The phantom was scanned using the prototype VTDA system for direct 3D reconstruction. Then the same phantom was scanned using a GE CT/i spiral CT scanner using the routine pulmonary CT angiography protocols. IV contrast injection and volume scanning protocols were developed during the dog studies. Both VTDA reconstructed images and spiral CT images of the specially designed phantom were analyzed and compared. The detectability of simulated vessels and clots was assessed as the function of iodine concentration levels, oriented angles, and diameters of the vessels and clots. A set of 3D VTDA reconstruction images of dog pulmonary arteries was obtained with different IV injection rates and isotropic resolution in the x, y and z directions. The results of clot detection studies in dog pulmonary arteries have also been shown. This study presents a new tomographic IV angiography imaging technique for cross sectional pulmonary angiography. The results of phantom and animal studies indicate that IV-VTDA is superior to spiral CT for cross sectional pulmonary angiography.

A data acquisition and control system for high-speed gamma-ray tomography

NASA Astrophysics Data System (ADS)

Hjertaker, B. T.; Maad, R.; Schuster, E.; Almås, O. A.; Johansen, G. A.

2008-09-01

A data acquisition and control system (DACS) for high-speed gamma-ray tomography based on the USB (Universal Serial Bus) and Ethernet communication protocols has been designed and implemented. The high-speed gamma-ray tomograph comprises five 500 mCi 241Am gamma-ray sources, each at a principal energy of 59.5 keV, which corresponds to five detector modules, each consisting of 17 CdZnTe detectors. The DACS design is based on Microchip's PIC18F4550 and PIC18F4620 microcontrollers, which facilitates an USB 2.0 interface protocol and an Ethernet (IEEE 802.3) interface protocol, respectively. By implementing the USB- and Ethernet-based DACS, a sufficiently high data acquisition rate is obtained and no dedicated hardware installation is required for the data acquisition computer, assuming that it is already equipped with a standard USB and/or Ethernet port. The API (Application Programming Interface) for the DACS is founded on the National Instrument's LabVIEW® graphical development tool, which provides a simple and robust foundation for further application software developments for the tomograph. The data acquisition interval, i.e. the integration time, of the high-speed gamma-ray tomograph is user selectable and is a function of the statistical measurement accuracy required for the specific application. The bandwidth of the DACS is 85 kBytes s-1 for the USB communication protocol and 28 kBytes s-1 for the Ethernet protocol. When using the iterative least square technique reconstruction algorithm with a 1 ms integration time, the USB-based DACS provides an online image update rate of 38 Hz, i.e. 38 frames per second, whereas 31 Hz for the Ethernet-based DACS. The off-line image update rate (storage to disk) for the USB-based DACS is 278 Hz using a 1 ms integration time. Initial characterization of the high-speed gamma-ray tomograph using the DACS on polypropylene phantoms is presented in the paper.

A New Approach to the Visual Rendering of Mantle Tomography

NASA Astrophysics Data System (ADS)

Holtzman, B. K.; Pratt, M. J.; Turk, M.; Hannasch, D. A.

2016-12-01

Visualization of mantle tomographic models requires a range of subjective aesthetic decisions that are often made subconsciously or unarticulated by authors. Many of these decisions affect the interpretations of the model, and therefore should be articulated and understood. In 2D these decisions are manifest in the choice of colormap, including the data values associated with the neutral/transitional colorband, as well as the correspondence between the extrema in the colormap and the parameters of the extrema. For example, we generally choose warm color signifying slow- and cool colors signifying fast velocities (or perturbations), but where is the transition, and the color gradients from transition to extrema? In 3D, volumes are generally rendered by choosing an isosurface of a velocity perturbation (relative to a model at each depth) and coloring it slow to fast. The choice of isosurface is arbitrary or guided by a researcher's intuition, again strongly affecting (or driven by) the interpretation. Here, we present a different approach to 3-D rendering of tomography models, using true volumetric rendering with "yt", a python package for visualization and analysis of data. In our approach, we do not use isosurfaces; instead, we render the extrema in the tomographic model as the most opaque, with an opacity function that touches zero (totally transparent) at dynamically selected values, or at the average value at each depth. The intent is that the most robust aspects of the model are visually clear, and the visualization emphasizes the nature of the interfaces between regions as well as the form of distinct mantle regions. Much of the current scientific discussion in upper mantle tomography focuses on the nature of interfaces, so we will demonstrate how decisions in the definition of the transparent regions influence interpretation of tomographic models. Our aim is to develop a visual language for tomographic visualization that can help focus geodynamic questions.

A comparison of newborn stylized and tomographic models for dose assessment in paediatric radiology

NASA Astrophysics Data System (ADS)

Staton, R. J.; Pazik, F. D.; Nipper, J. C.; Williams, J. L.; Bolch, W. E.

2003-04-01

Establishment of organ doses from diagnostic and interventional examinations is a key component to quantifying the radiation risks from medical exposures and for formulating corresponding dose-reduction strategies. Radiation transport models of human anatomy provide a convenient method for simulating radiological examinations. At present, two classes of models exist: stylized mathematical models and tomographic voxel models. In the present study, organ dose comparisons are made for projection radiographs of both a stylized and a tomographic model of the newborn patient. Sixteen separate radiographs were simulated for each model at x-ray technique factors typical of newborn examinations: chest, abdomen, thorax and head views in the AP, PA, left LAT and right LAT projection orientation. For AP and PA radiographs of the torso (chest, abdomen and thorax views), the effective dose assessed for the tomographic model exceeds that for the stylized model with per cent differences ranging from 19% (AP abdominal view) to 43% AP chest view. In contrast, the effective dose for the stylized model exceeds that for the tomographic model for all eight lateral views including those of the head, with per cent differences ranging from 9% (LLAT chest view) to 51% (RLAT thorax view). While organ positioning differences do exist between the models, a major factor contributing to differences in effective dose is the models' exterior trunk shape. In the tomographic model, a more elliptical shape is seen thus providing for less tissue shielding for internal organs in the AP and PA directions, with corresponding increased tissue shielding in the lateral directions. This observation is opposite of that seen in comparisons of stylized and tomographic models of the adult.

High-Energy, High-Pulse-Rate Light Sources for Enhanced Time-Resolved Tomographic PIV of Unsteady and Turbulent Flows

DTIC Science & Technology

2017-07-31

Report: High-Energy, High-Pulse-Rate Light Sources for Enhanced Time -Resolved Tomographic PIV of Unsteady & Turbulent Flows The views, opinions and/or...reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching...High-Energy, High-Pulse-Rate Light Sources for Enhanced Time -Resolved Tomographic PIV of Unsteady & Turbulent Flows Report Term: 0-Other Email

A new approach to interpretation of heterogeneity of fluorescence decay in complex biological systems

NASA Astrophysics Data System (ADS)

Wlodarczyk, Jakub; Kierdaszuk, Borys

2005-08-01

Decays of tyrosine fluorescence in protein-ligand complexes are described by a model of continuous distribution of fluorescence lifetimes. Resulted analytical power-like decay function provides good fits to highly complex fluorescence kinetics. Moreover, this is a manifestation of so-called Tsallis q-exponential function, which is suitable for description of the systems with long-range interactions, memory effect, as well as with fluctuations of the characteristic lifetime of fluorescence. The proposed decay functions were applied to analysis of fluorescence decays of tyrosine in a protein, i.e. the enzyme purine nucleoside phosphorylase from E. coli (the product of the deoD gene), free in aqueous solution and in a complex with formycin A (an inhibitor) and orthophosphate (a co-substrate). The power-like function provides new information about enzyme-ligand complex formation based on the physically justified heterogeneity parameter directly related to the lifetime distribution. A measure of the heterogeneity parameter in the enzyme systems is provided by a variance of fluorescence lifetime distribution. The possible number of deactivation channels and excited state mean lifetime can be easily derived without a priori knowledge of the complexity of studied system. Moreover, proposed model is simpler then traditional multi-exponential one, and better describes heterogeneous nature of studied systems.

Chemical imaging analysis of the brain with X-ray methods

NASA Astrophysics Data System (ADS)

Collingwood, Joanna F.; Adams, Freddy

2017-04-01

Cells employ various metal and metalloid ions to augment the structure and the function of proteins and to assist with vital biological processes. In the brain they mediate biochemical processes, and disrupted metabolism of metals may be a contributing factor in neurodegenerative disorders. In this tutorial review we will discuss the particular role of X-ray methods for elemental imaging analysis of accumulated metal species and metal-containing compounds in biological materials, in the context of post-mortem brain tissue. X-rays have the advantage that they have a short wavelength and can penetrate through a thick biological sample. Many of the X-ray microscopy techniques that provide the greatest sensitivity and specificity for trace metal concentrations in biological materials are emerging at synchrotron X-ray facilities. Here, the extremely high flux available across a wide range of soft and hard X-rays, combined with state-of-the-art focusing techniques and ultra-sensitive detectors, makes it viable to undertake direct imaging of a number of elements in brain tissue. The different methods for synchrotron imaging of metals in brain tissues at regional, cellular, and sub-cellular spatial resolution are discussed. Methods covered include X-ray fluorescence for elemental imaging, X-ray absorption spectrometry for speciation imaging, X-ray diffraction for structural imaging, phase contrast for enhanced contrast imaging and scanning transmission X-ray microscopy for spectromicroscopy. Two- and three-dimensional (confocal and tomographic) imaging methods are considered as well as the correlation of X-ray microscopy with other imaging tools.

Alexandrite as a high-temperature pressure calibrant, and implications for the ruby-fluorescence scale

NASA Technical Reports Server (NTRS)

Jahren, A. H.; Kruger, M. B.; Jeanloz, Raymond

1992-01-01

The wavelength shifts of the R1 and R2 fluorescence lines of alexandrite (BeAl2O4:Cr(+3)) have been experimentally calibrated against the ruby-fluorescence scale as a function of both hydrostatic and nonhydrostatic pressures between 0 and 50 GPa, and simultaneously as a function of temperatures between 290 and 550 K. It is found that the pressure-temperature cross derivative of the fluorescence wavelength shifts are negligible for both ruby and alexandrite.

Equation for wave processes in inhomogeneous moving media and functional solution of the acoustic tomography problem based on it

NASA Astrophysics Data System (ADS)

Rumyantseva, O. D.; Shurup, A. S.

2017-01-01

The paper considers the derivation of the wave equation and Helmholtz equation for solving the tomographic problem of reconstruction combined scalar-vector inhomogeneities describing perturbations of the sound velocity and absorption, the vector field of flows, and perturbations of the density of the medium. Restrictive conditions under which the obtained equations are meaningful are analyzed. Results of numerical simulation of the two-dimensional functional-analytical Novikov-Agaltsov algorithm for reconstructing the flow velocity using the the obtained Helmholtz equation are presented.

Fluorescent 2D WS2 Nanosheets Bearing Chemical Affinity Elements for the Recognition of Glycated Hemoglobin.

PubMed

Yang, Jin-Kyoung; Lee, Hye-Rim; Hwang, In-Jun; Kim, Hye-In; Yim, DaBin; Kim, Jong-Ho

2018-05-14

It is required to exfoliate and functionalize 2D transition metal dichalcogenides (TMDs) in an aqueous solution for biological and medical applications. Herein, the approach for the simultaneous exfoliation and functionalization of 2D WS 2 nanosheets using boronic acid-modified poly(vinyl alcohol) (B-PVA) in an aqueous solution is reported, and the B-PVA-functionalized WS 2 nanosheets (B-PVA-WS 2 ) are exploited as a fluorescent biosensor for the detection of glycated hemoglobin, HbA1c. The synthetic B-PVA polymer facilitates the exfoliation and functionalization of WS 2 nanosheets from the bulk counterpart in the aqueous solution via a pulsed sonication process, resulting in fluorescent B-PVA-WS 2 nanohybrids with a specific recognition of HbA1c. The fluorescence of the B-PVA-WS 2 is quenched in the presence of HbA1c, whereas PVA-functionalized WS 2 (PVA-WS 2 ), not bearing boronic acid as a recognition moiety, shows no fluorescence changes upon the addition of the target. The B-PVA-WS 2 is able to selectively detect HbA1c at the concentration as low as 3.3 × 10 -8 m based on its specific fluorescence quenching. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

In Vivo Imaging of Flavoprotein Fluorescence During Hypoxia Reveals the Importance of Direct Arterial Oxygen Supply to Cerebral Cortex Tissue.

PubMed

Chisholm, K I; Ida, K K; Davies, A L; Papkovsky, D B; Singer, M; Dyson, A; Tachtsidis, I; Duchen, M R; Smith, K J

2016-01-01

Live imaging of mitochondrial function is crucial to understand the important role played by these organelles in a wide range of diseases. The mitochondrial redox potential is a particularly informative measure of mitochondrial function, and can be monitored using the endogenous green fluorescence of oxidized mitochondrial flavoproteins. Here, we have observed flavoprotein fluorescence in the exposed murine cerebral cortex in vivo using confocal imaging; the mitochondrial origin of the signal was confirmed using agents known to manipulate mitochondrial redox potential. The effects of cerebral oxygenation on flavoprotein fluorescence were determined by manipulating the inspired oxygen concentration. We report that flavoprotein fluorescence is sensitive to reductions in cortical oxygenation, such that reductions in inspired oxygen resulted in loss of flavoprotein fluorescence with the exception of a preserved 'halo' of signal in periarterial regions. The findings are consistent with reports that arteries play an important role in supplying oxygen directly to tissue in the cerebral cortex, maintaining mitochondrial function.

Tomographic imaging of subducted lithosphere below northwest Pacific island arcs

USGS Publications Warehouse

Van Der Hilst, R.; Engdahl, R.; Spakman, W.; Nolet, G.

1991-01-01

The seismic tomography problem does not have a unique solution, and published tomographic images have been equivocal with regard to the deep structure of subducting slabs. An improved tomographic method, using a more realistic background Earth model and surf ace-reflected as well as direct seismic phases, shows that slabs beneath the Japan and Izu Bonin island arcs are deflected at the boundary between upper and lower mantle, whereas those beneath the northern Kuril and Mariana arcs sink into the lower mantle.

Business aspects of cardiovascular computed tomography: tackling the challenges.

PubMed

Bateman, Timothy M

2008-01-01

The purpose of this article is to provide a comprehensive understanding of the business issues surrounding provision of dedicated cardiovascular computed tomographic imaging. Some of the challenges include high up-front costs, current low utilization relative to scanner capability, and inadequate payments. Cardiovascular computed tomographic imaging is a valuable clinical modality that should be offered by cardiovascular centers-of-excellence. With careful consideration of the business aspects, moderate-to-large size cardiology programs should be able to implement an economically viable cardiovascular computed tomographic service.

3D "spectracoustic" system: a modular, tomographic, spectroscopic mapping imaging, non-invasive, diagnostic system for detection of small starting developing tumors like melanoma

NASA Astrophysics Data System (ADS)

Karagiannis, Georgios

2017-03-01

This work led to a new method named 3D spectracoustic tomographic mapping imaging. The current and the future work is related to the fabrication of a combined acoustic microscopy transducer and infrared illumination probe permitting the simultaneous acquisition of the spectroscopic and the tomographic information. This probe provides with the capability of high fidelity and precision registered information from the combined modalities named spectracoustic information.

Tomographic diffractive microscopy with agile illuminations for imaging targets in a noisy background.

PubMed

Zhang, T; Godavarthi, C; Chaumet, P C; Maire, G; Giovannini, H; Talneau, A; Prada, C; Sentenac, A; Belkebir, K

2015-02-15

Tomographic diffractive microscopy is a marker-free optical digital imaging technique in which three-dimensional samples are reconstructed from a set of holograms recorded under different angles of incidence. We show experimentally that, by processing the holograms with singular value decomposition, it is possible to image objects in a noisy background that are invisible with classical wide-field microscopy and conventional tomographic reconstruction procedure. The targets can be further characterized with a selective quantitative inversion.

The accuracy of tomographic particle image velocimetry for measurements of a turbulent boundary layer

NASA Astrophysics Data System (ADS)

Atkinson, Callum; Coudert, Sebastien; Foucaut, Jean-Marc; Stanislas, Michel; Soria, Julio

2011-04-01

To investigate the accuracy of tomographic particle image velocimetry (Tomo-PIV) for turbulent boundary layer measurements, a series of synthetic image-based simulations and practical experiments are performed on a high Reynolds number turbulent boundary layer at Reθ = 7,800. Two different approaches to Tomo-PIV are examined using a full-volume slab measurement and a thin-volume "fat" light sheet approach. Tomographic reconstruction is performed using both the standard MART technique and the more efficient MLOS-SMART approach, showing a 10-time increase in processing speed. Random and bias errors are quantified under the influence of the near-wall velocity gradient, reconstruction method, ghost particles, seeding density and volume thickness, using synthetic images. Experimental Tomo-PIV results are compared with hot-wire measurements and errors are examined in terms of the measured mean and fluctuating profiles, probability density functions of the fluctuations, distributions of fluctuating divergence through the volume and velocity power spectra. Velocity gradients have a large effect on errors near the wall and also increase the errors associated with ghost particles, which convect at mean velocities through the volume thickness. Tomo-PIV provides accurate experimental measurements at low wave numbers; however, reconstruction introduces high noise levels that reduces the effective spatial resolution. A thinner volume is shown to provide a higher measurement accuracy at the expense of the measurement domain, albeit still at a lower effective spatial resolution than planar and Stereo-PIV.

Visual computed tomographic scoring of emphysema and its correlation with its diagnostic electrocardiographic sign: the frontal P vector.

PubMed

Chhabra, Lovely; Sareen, Pooja; Gandagule, Amit; Spodick, David H

2012-03-01

Verticalization of the frontal P vector in patients older than 45 years is virtually diagnostic of pulmonary emphysema (sensitivity, 96%; specificity, 87%). We investigated the correlation of P vector and the computed tomographic visual score of emphysema (VSE) in patients with established diagnosis of chronic obstructive pulmonary disease/emphysema. High-resolution computed tomographic scans of 26 patients with emphysema (age, >45 years) were reviewed to assess the type and extent of emphysema using the subjective visual scoring. Electrocardiograms were independently reviewed to determine the frontal P vector. The P vector and VSE were compared for statistical correlation. Both P vector and VSE were also directly compared with the forced expiratory volume at 1 second. The VSE and the orientation of the P vector (ÂP) had an overall significant positive correlation (r = +0.68; P = .0001) in all patients, but the correlation was very strong in patients with predominant lower-lobe emphysema (r = +0.88; P = .0004). Forced expiratory volume at 1 second and ÂP had almost a linear inverse correlation in predominant lower-lobe emphysema (r = -0.92; P < .0001). Orientation of the P vector positively correlates with visually scored emphysema. Both ÂP and VSE are strong reflectors of qualitative lung function in patients with predominant lower-lobe emphysema. A combination of more vertical ÂP and predominant lower-lobe emphysema reflects severe obstructive lung dysfunction. Copyright © 2012 Elsevier Inc. All rights reserved.

Effect of Donepezil on Wernicke Aphasia After Bilateral Middle Cerebral Artery Infarction: Subtraction Analysis of Brain F-18 Fluorodeoxyglucose Positron Emission Tomographic Images.

PubMed

Yoon, Seo Yeon; Kim, Je-Kyung; An, Young-Sil; Kim, Yong Wook

2015-01-01

Aphasia is one of the most common neurologic deficits occurring after stroke. Although the speech-language therapy is a mainstream option for poststroke aphasia, pharmacotherapy is recently being tried to modulate different neurotransmitter systems. However, the efficacy of those treatments is still controversial. We present a case of a 53-year-old female patient with Wernicke aphasia, after the old infarction in the territory of left middle cerebral artery for 8 years and the recent infarction in the right middle cerebral artery for 4 months. On the initial evaluation, the Aphasia Quotient in Korean version of the Western Aphasia Battery was 25.6 of 100. Baseline brain F-18 fluorodeoxyglucose positron emission tomographic images demonstrated a decreased cerebral metabolism in the left temporoparietal area and right temporal lobe. Donepezil hydrochloride, a reversible acetylcholinesterase inhibitor, was orally administered 5 mg/d for 6 weeks after the initial evaluation and was increased to 10 mg/d for the following 6 weeks. After the donepezil treatment, the patient showed improvement in language function, scoring 51.0 of 100 on Aphasia Quotient. A subtraction analysis of the brain F-18 fluorodeoxyglucose positron emission tomographic images after donepezil medication demonstrated increased uptake in both middle temporal gyri, extended to the occipital area and the left cerebellum. Thus, we suggest that donepezil can be an effective therapeutic choice for the treatment of Wernicke aphasia.

3D reconstruction of the magnetic vector potential using model based iterative reconstruction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prabhat, K. C.; Aditya Mohan, K.; Phatak, Charudatta

Lorentz transmission electron microscopy (TEM) observations of magnetic nanoparticles contain information on the magnetic and electrostatic potentials. Vector field electron tomography (VFET) can be used to reconstruct electromagnetic potentials of the nanoparticles from their corresponding LTEM images. The VFET approach is based on the conventional filtered back projection approach to tomographic reconstructions and the availability of an incomplete set of measurements due to experimental limitations means that the reconstructed vector fields exhibit significant artifacts. In this paper, we outline a model-based iterative reconstruction (MBIR) algorithm to reconstruct the magnetic vector potential of magnetic nanoparticles. We combine a forward model formore » image formation in TEM experiments with a prior model to formulate the tomographic problem as a maximum a-posteriori probability estimation problem (MAP). The MAP cost function is minimized iteratively to determine the vector potential. Here, a comparative reconstruction study of simulated as well as experimental data sets show that the MBIR approach yields quantifiably better reconstructions than the VFET approach.« less

Classification of JET Neutron and Gamma Emissivity Profiles

NASA Astrophysics Data System (ADS)

Craciunescu, T.; Murari, A.; Kiptily, V.; Vega, J.; Contributors, JET

2016-05-01

In thermonuclear plasmas, emission tomography uses integrated measurements along lines of sight (LOS) to determine the two-dimensional (2-D) spatial distribution of the volume emission intensity. Due to the availability of only a limited number views and to the coarse sampling of the LOS, the tomographic inversion is a limited data set problem. Several techniques have been developed for tomographic reconstruction of the 2-D gamma and neutron emissivity on JET. In specific experimental conditions the availability of LOSs is restricted to a single view. In this case an explicit reconstruction of the emissivity profile is no longer possible. However, machine learning classification methods can be used in order to derive the type of the distribution. In the present approach the classification is developed using the theory of belief functions which provide the support to fuse the results of independent clustering and supervised classification. The method allows to represent the uncertainty of the results provided by different independent techniques, to combine them and to manage possible conflicts.

3D reconstruction of the magnetic vector potential using model based iterative reconstruction.

PubMed

Prabhat, K C; Aditya Mohan, K; Phatak, Charudatta; Bouman, Charles; De Graef, Marc

2017-11-01

Lorentz transmission electron microscopy (TEM) observations of magnetic nanoparticles contain information on the magnetic and electrostatic potentials. Vector field electron tomography (VFET) can be used to reconstruct electromagnetic potentials of the nanoparticles from their corresponding LTEM images. The VFET approach is based on the conventional filtered back projection approach to tomographic reconstructions and the availability of an incomplete set of measurements due to experimental limitations means that the reconstructed vector fields exhibit significant artifacts. In this paper, we outline a model-based iterative reconstruction (MBIR) algorithm to reconstruct the magnetic vector potential of magnetic nanoparticles. We combine a forward model for image formation in TEM experiments with a prior model to formulate the tomographic problem as a maximum a-posteriori probability estimation problem (MAP). The MAP cost function is minimized iteratively to determine the vector potential. A comparative reconstruction study of simulated as well as experimental data sets show that the MBIR approach yields quantifiably better reconstructions than the VFET approach. Copyright © 2017 Elsevier B.V. All rights reserved.

Protein secondary structure determination by constrained single-particle cryo-electron tomography.

PubMed

Bartesaghi, Alberto; Lecumberry, Federico; Sapiro, Guillermo; Subramaniam, Sriram

2012-12-05

Cryo-electron microscopy (cryo-EM) is a powerful technique for 3D structure determination of protein complexes by averaging information from individual molecular images. The resolutions that can be achieved with single-particle cryo-EM are frequently limited by inaccuracies in assigning molecular orientations based solely on 2D projection images. Tomographic data collection schemes, however, provide powerful constraints that can be used to more accurately determine molecular orientations necessary for 3D reconstruction. Here, we propose "constrained single-particle tomography" as a general strategy for 3D structure determination in cryo-EM. A key component of our approach is the effective use of images recorded in tilt series to extract high-resolution information and correct for the contrast transfer function. By incorporating geometric constraints into the refinement to improve orientational accuracy of images, we reduce model bias and overrefinement artifacts and demonstrate that protein structures can be determined at resolutions of ∼8 Å starting from low-dose tomographic tilt series. Copyright © 2012 Elsevier Ltd. All rights reserved.

3D reconstruction of the magnetic vector potential using model based iterative reconstruction

DOE PAGES

Prabhat, K. C.; Aditya Mohan, K.; Phatak, Charudatta; ...

2017-07-03

Lorentz transmission electron microscopy (TEM) observations of magnetic nanoparticles contain information on the magnetic and electrostatic potentials. Vector field electron tomography (VFET) can be used to reconstruct electromagnetic potentials of the nanoparticles from their corresponding LTEM images. The VFET approach is based on the conventional filtered back projection approach to tomographic reconstructions and the availability of an incomplete set of measurements due to experimental limitations means that the reconstructed vector fields exhibit significant artifacts. In this paper, we outline a model-based iterative reconstruction (MBIR) algorithm to reconstruct the magnetic vector potential of magnetic nanoparticles. We combine a forward model formore » image formation in TEM experiments with a prior model to formulate the tomographic problem as a maximum a-posteriori probability estimation problem (MAP). The MAP cost function is minimized iteratively to determine the vector potential. Here, a comparative reconstruction study of simulated as well as experimental data sets show that the MBIR approach yields quantifiably better reconstructions than the VFET approach.« less

Fabrication of transferrin functionalized gold nanoclusters/graphene oxide nanocomposite for turn-on near-infrared fluorescent bioimaging of cancer cells and small animals.

PubMed

Wang, Yong; Chen, Jia-Tong; Yan, Xiu-Ping

2013-02-19

Transferrin (Tf)-functionalized gold nanoclusters (Tf-AuNCs)/graphene oxide (GO) nanocomposite (Tf-AuNCs/GO) was fabricated as a turn-on near-infrared (NIR) fluorescent probe for bioimaging cancer cells and small animals. A one-step approach was developed to prepare Tf-AuNCs via a biomineralization process with Tf as the template. Tf acted not only as a stabilizer and a reducer but also as a functional ligand for targeting the transferrin receptor (TfR). The prepared Tf-AuNCs gave intense NIR fluorescence that can avoid interference from biological media such as tissue autofluorescence and scattering light. The assembly of Tf-AuNCs and GO gave the Tf-AuNCs/GO nanocomposite, a turn-on NIR fluorescent probe with negligible background fluorescence due to the super fluorescence quenching property of GO. The NIR fluorescence of the Tf-AuNCs/GO nanocomposite was effectively restored in the presence of TfR, due to the specific interaction between Tf and TfR and the competition of TfR with the GO for the Tf in Tf-AuNCs/GO composite. The developed turn-on NIR fluorescence probe offered excellent water solubility, stability, and biocompatibility, and exhibited high specificity to TfR with negligible cytotoxicity. The probe was successfully applied for turn-on fluorescent bioimaging of cancer cells and small animals.

An imidazole functionalized pentameric thiophene displays different staining patterns in normal and malignant cells

NASA Astrophysics Data System (ADS)

Nilsson, Peter; Magnusson, Karin; Appelqvist, Hanna; Cieslar-Pobuda, Artur; Bäck, Marcus; Kågedal, Bertil; Jonasson, Jon; Los, Marek

2015-10-01

Molecular tools for fluorescent imaging of cells and their components are vital for understanding the function and activity of cells. Here, we report an imidazole functionalized pentameric oligothiophene, p-HTIm, that can be utilized for fluorescent imaging of cells. p-HTIm fluorescence in normal cells appeared in a peripheral punctate pattern partially co-localized with lysosomes, whereas a one-sided perinuclear Golgi associated localization of the dye was observed in malignant cells. The uptake of p-HTIm was temperature dependent and the intracellular target was reached within 1 h after staining. The ability of p-HTIm to stain cells was reduced when the imidazole side chain was chemically altered, verifying that specific imidazole side-chain functionalities are necessary for achieving the observed cellular staining. Our findings confirm that properly functionalized oligothiophenes can be utilized as fluorescent tools for vital staining of cells and that the selectivity towards distinct intracellular targets are highly dependent on the side-chain functionalities along the conjugated thiophene backbone.

Evaluation of functioning of mitochondrial electron transport chain with NADH and FAD autofluorescence

PubMed

Danylovych, H V

2016-01-01

We prove the feasibility of evaluation of mitochondrial electron transport chain function in isolated mitochondria of smooth muscle cells of rats from uterus using fluorescence of NADH and FAD coenzymes. We found the inversely directed changes in FAD and NADH fluorescence intensity under normal functioning of mitochondrial electron transport chain. The targeted effect of inhibitors of complex I, III and IV changed fluorescence of adenine nucleotides. Rotenone (5 μM) induced rapid increase in NADH fluorescence due to inhibition of complex I, without changing in dynamics of FAD fluorescence increase. Antimycin A, a complex III inhibitor, in concentration of 1 μg/ml caused sharp increase in NADH fluorescence and moderate increase in FAD fluorescence in comparison to control. NaN3 (5 mM), a complex IV inhibitor, and CCCP (10 μM), a protonophore, caused decrease in NADH and FAD fluorescence. Moreover, all the inhibitors caused mitochondria swelling. NO donors, e.g. 0.1 mM sodium nitroprusside and sodium nitrite similarly to the effects of sodium azide. Energy-dependent Ca2+ accumulation in mitochondrial matrix (in presence of oxidation substrates and Mg-ATP2- complex) is associated with pronounced drop in NADH and FAD fluorescence followed by increased fluorescence of adenine nucleotides, which may be primarily due to Ca2+- dependent activation of dehydrogenases of citric acid cycle. Therefore, the fluorescent signal of FAD and NADH indicates changes in oxidation state of these nucleotides in isolated mitochondria, which may be used to assay the potential of effectors of electron transport chain.

Assessment of a New High-Performance Small-Animal X-Ray Tomograph

NASA Astrophysics Data System (ADS)

Vaquero, J. J.; Redondo, S.; Lage, E.; Abella, M.; Sisniega, A.; Tapias, G.; Montenegro, M. L. Soto; Desco, M.

2008-06-01

We have developed a new X-ray cone-beam tomograph for in vivo small-animal imaging using a flat panel detector (CMOS technology with a microcolumnar CsI scintillator plate) and a microfocus X-ray source. The geometrical configuration was designed to achieve a spatial resolution of about 12 lpmm with a field of view appropriate for laboratory rodents. In order to achieve high performance with regard to per-animal screening time and cost, the acquisition software takes advantage of the highest frame rate of the detector and performs on-the-fly corrections on the detector raw data. These corrections include geometrical misalignments, sensor non-uniformities, and defective elements. The resulting image is then converted to attenuation values. We measured detector modulation transfer function (MTF), detector stability, system resolution, quality of the reconstructed tomographic images and radiated dose. The system resolution was measured following the standard test method ASTM E 1695 -95. For image quality evaluation, we assessed signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) as a function of the radiated dose. Dose studies for different imaging protocols were performed by introducing TLD dosimeters in representative organs of euthanized laboratory rats. Noise figure, measured as standard deviation, was 50 HU for a dose of 10 cGy. Effective dose with standard research protocols is below 200 mGy, confirming that the system is appropriate for in vivo imaging. Maximum spatial resolution achieved was better than 50 micron. Our experimental results obtained with image quality phantoms as well as with in-vivo studies show that the proposed configuration based on a CMOS flat panel detector and a small micro-focus X-ray tube leads to a compact design that provides good image quality and low radiated dose, and it could be used as an add-on for existing PET or SPECT scanners.

Seismic imaging: From classical to adjoint tomography

NASA Astrophysics Data System (ADS)

Liu, Q.; Gu, Y. J.

2012-09-01

Seismic tomography has been a vital tool in probing the Earth's internal structure and enhancing our knowledge of dynamical processes in the Earth's crust and mantle. While various tomographic techniques differ in data types utilized (e.g., body vs. surface waves), data sensitivity (ray vs. finite-frequency approximations), and choices of model parameterization and regularization, most global mantle tomographic models agree well at long wavelengths, owing to the presence and typical dimensions of cold subducted oceanic lithospheres and hot, ascending mantle plumes (e.g., in central Pacific and Africa). Structures at relatively small length scales remain controversial, though, as will be discussed in this paper, they are becoming increasingly resolvable with the fast expanding global and regional seismic networks and improved forward modeling and inversion techniques. This review paper aims to provide an overview of classical tomography methods, key debates pertaining to the resolution of mantle tomographic models, as well as to highlight recent theoretical and computational advances in forward-modeling methods that spearheaded the developments in accurate computation of sensitivity kernels and adjoint tomography. The first part of the paper is devoted to traditional traveltime and waveform tomography. While these approaches established a firm foundation for global and regional seismic tomography, data coverage and the use of approximate sensitivity kernels remained as key limiting factors in the resolution of the targeted structures. In comparison to classical tomography, adjoint tomography takes advantage of full 3D numerical simulations in forward modeling and, in many ways, revolutionizes the seismic imaging of heterogeneous structures with strong velocity contrasts. For this reason, this review provides details of the implementation, resolution and potential challenges of adjoint tomography. Further discussions of techniques that are presently popular in seismic array analysis, such as noise correlation functions, receiver functions, inverse scattering imaging, and the adaptation of adjoint tomography to these different datasets highlight the promising future of seismic tomography.

Lamb-Wave-Based Tomographic Imaging Techniques for Hole-Edge Corrosion Monitoring in Plate Structures

PubMed Central

Wang, Dengjiang; Zhang, Weifang; Wang, Xiangyu; Sun, Bo

2016-01-01

This study presents a novel monitoring method for hole-edge corrosion damage in plate structures based on Lamb wave tomographic imaging techniques. An experimental procedure with a cross-hole layout using 16 piezoelectric transducers (PZTs) was designed. The A0 mode of the Lamb wave was selected, which is sensitive to thickness-loss damage. The iterative algebraic reconstruction technique (ART) method was used to locate and quantify the corrosion damage at the edge of the hole. Hydrofluoric acid with a concentration of 20% was used to corrode the specimen artificially. To estimate the effectiveness of the proposed method, the real corrosion damage was compared with the predicted corrosion damage based on the tomographic method. The results show that the Lamb-wave-based tomographic method can be used to monitor the hole-edge corrosion damage accurately. PMID:28774041

Vectors for fluorescent protein tagging in Phytophthora: tools for functional genomics and cell biology.

PubMed

Ah-Fong, Audrey M V; Judelson, Howard S

2011-09-01

Fluorescent tagging has become the strategy of choice for examining the subcellular localisation of proteins. To develop a versatile community resource for this method in oomycetes, plasmids were constructed that allow the expression of either of four spectrally distinct proteins [cyan fluorescent protein (CFP), green fluorescent protein (GFP), yellow fluorescent protein (YFP), and mCherry], alone or fused at their N- or C-termini, to sequences of interest. Equivalent sets of plasmids were made using neomycin or hygromycin phosphotransferases (nptII, hpt) as selectable markers, to facilitate double-labelling and aid work in diverse species. The fluorescent proteins and drug-resistance markers were fused to transcriptional regulatory sequences from the oomycete Bremia lactucae, which are known to function in diverse oomycetes, although the promoter in the fluorescence cassette (ham34) can be replaced easily by a promoter of interest. The function of each plasmid was confirmed in Phytophthora infestans. Moreover, fusion proteins were generated using targeting sequences for the endoplasmic reticulum, Golgi, mitochondria, nuclei, and peroxisomes. Studies of the distribution of the fusions in mycelia and sporangia provided insight into cellular organisation at different stages of development. This toolbox of vectors should advance studies of gene function and cell biology in Phytophthora and other oomycetes. Copyright © 2011 British Mycological Society. Published by Elsevier Ltd. All rights reserved.

Construction of dual-functional polymer nanomaterials with near-infrared fluorescence imaging and polymer prodrug by RAFT-mediated aqueous dispersion polymerization.

PubMed

Tian, Chun; Niu, Jinyun; Wei, Xuerui; Xu, Yujie; Zhang, Lifen; Cheng, Zhenping; Zhu, Xiulin

2018-05-31

The performance of functional polymer nanomaterials is a vigorously discussed topic in polymer science. We devoted ourselves to investigating polymer nanomaterials based on near-infrared (NIR) fluorescence imaging and polymer prodrug in this study. Aza-boron dipyrromethene (BODIPY) is an important organic dye, having characteristics such as environmental resistance, light resistance, high molar extinction coefficient, and fluorescence quantum yield. We incorporated it into our target monomer, which can be polymerized without changing its parent structure in a polar solvent and copolymerized with water-soluble monomer to improve the solubility of the dye in an aqueous solution. At the same time, the hydrophobic drug camptothecin (CPT) was designed as a prodrug monomer, and the polymeric nanoparticles (NPs) with NIR fluorescence imaging and prodrug were synthesized in situ in reversible addition-fragmentation chain transfer (RAFT)-mediated aqueous dispersion polymerization. The dynamic light scattering (DLS) and transmission electron microscopy (TEM) revealed the final uniform size of the dual-functional polymeric NPs morphology. The dual-functional polymeric NPs had a strong absorption and emission signal in the NIR region (>650 nm) based on the fluorescence tests. In consideration of the long-term biological toxicity, confocal laser scanning microscopy (CLSM) results indicated that the dual-functional NPs with controlled drug content exhibited effective capability of killing HeLa cells. In addition, in vivo imaging of the dual-functional NPs was observed in real time, and the fluorescent signals clearly demonstrated the dynamic process of prodrug transfer.

Fluorescence-Guided Probes of Aptamer-Targeted Gold Nanoparticles with Computed Tomography Imaging Accesses for in Vivo Tumor Resection.

PubMed

Li, Cheng-Hung; Kuo, Tsung-Rong; Su, Hsin-Jan; Lai, Wei-Yun; Yang, Pan-Chyr; Chen, Jinn-Shiun; Wang, Di-Yan; Wu, Yi-Chun; Chen, Chia-Chun

2015-10-28

Recent development of molecular imaging probes for fluorescence-guided surgery has shown great progresses for determining tumor margin to execute the tissue resection. Here we synthesize the fluorescent gold nanoparticles conjugated with diatrizoic acid and nucleolin-targeted AS1411 aptamer. The nanoparticle conjugates exhibit high water-solubility, good biocompatibility, visible fluorescence and strong X-ray attenuation for computed tomography (CT) contrast enhancement. The fluorescent nanoparticle conjugates are applied as a molecular contrast agent to reveal the tumor location in CL1-5 tumor-bearing mice by CT imaging. Furthermore, the orange-red fluorescence emitting from the conjugates in the CL1-5 tumor can be easily visualized by the naked eyes. After the resection, the IVIS measurements show that the fluorescence signal of the nanoparticle conjugates in the tumor is greatly enhanced in comparison to that in the controlled experiment. Our work has shown potential application of functionalized nanoparticles as a dual-function imaging agent in clinical fluorescence-guided surgery.

Fluorescence-Guided Probes of Aptamer-Targeted Gold Nanoparticles with Computed Tomography Imaging Accesses for in Vivo Tumor Resection

PubMed Central

Li, Cheng-Hung; Kuo, Tsung-Rong; Su, Hsin-Jan; Lai, Wei-Yun; Yang, Pan-Chyr; Chen, Jinn-Shiun; Wang, Di-Yan; Wu, Yi-Chun; Chen, Chia-Chun

2015-01-01

Recent development of molecular imaging probes for fluorescence-guided surgery has shown great progresses for determining tumor margin to execute the tissue resection. Here we synthesize the fluorescent gold nanoparticles conjugated with diatrizoic acid and nucleolin-targeted AS1411 aptamer. The nanoparticle conjugates exhibit high water-solubility, good biocompatibility, visible fluorescence and strong X-ray attenuation for computed tomography (CT) contrast enhancement. The fluorescent nanoparticle conjugates are applied as a molecular contrast agent to reveal the tumor location in CL1-5 tumor-bearing mice by CT imaging. Furthermore, the orange-red fluorescence emitting from the conjugates in the CL1-5 tumor can be easily visualized by the naked eyes. After the resection, the IVIS measurements show that the fluorescence signal of the nanoparticle conjugates in the tumor is greatly enhanced in comparison to that in the controlled experiment. Our work has shown potential application of functionalized nanoparticles as a dual-function imaging agent in clinical fluorescence-guided surgery. PMID:26507179

Magneto-Fluorescent Core-Shell Supernanoparticles

PubMed Central

Chen, Ou; Riedemann, Lars; Etoc, Fred; Herrmann, Hendrik; Coppey, Mathieu; Barch, Mariya; Farrar, Christian T.; Zhao, Jing; Bruns, Oliver T.; Wei, He; Guo, Peng; Cui, Jian; Jensen, Russ; Chen, Yue; Harris, Daniel K.; Cordero, Jose M.; Wang, Zhongwu; Jasanoff, Alan; Fukumura, Dai; Reimer, Rudolph; Dahan, Maxime; Jain, Rakesh K.; Bawendi, Moungi G.

2014-01-01

Magneto-fluorescent particles have been recognized as an emerging class of materials that exhibit great potential in advanced applications. However, synthesizing such magneto-fluorescent nanomaterials that simultaneously exhibit uniform and tunable sizes, high magnetic content loading, maximized fluorophore coverage at the surface, and a versatile surface functionality has proven challenging. Here we report a simple approach for co-assembling magnetic nanoparticles with fluorescent quantum dots to form colloidal magneto-fluorescent supernanoparticles. Importantly, these supernanoparticles exhibit a superstructure consisting of a close packed magnetic nanoparticle “core” which is fully surrounded by a “shell” of fluorescent quantum dots. A thin layer of silica-coating provides high colloidal stability and biocompatiblity and a versatile surface functionality. We demonstrate that after surface pegylation, these silica-coated magneto-fluorescent supernanoparticles can be magnetically manipulated inside living cells while being optically tracked. Moreover, our silica-coated magneto-fluorescent supernanoparticles can also serve as an in vivo multi-photon and magnetic resonance dual-modal imaging probe. PMID:25298155

Crustal Structure of Indonesia from Seismic Ambient Noise Tomography

NASA Astrophysics Data System (ADS)

Saygin, E.; Cummins, P. R.; Suhardjono, S.; Nishida, K.

2012-12-01

We image a region spanning from south Vietnam to north Australia using over 300 seismic stations by using ambient seismic noise cross-correlations. The backbone of the network is formed by using the broadband seismograph network of Indonesia with over 160 stations serving as mid-tie point in the region. The retrieved Green's functions from the cross-correlation of continuously recorded seismic ambient noise at the stations are used to perform surface wave dispersion analysis. We apply a multiple filter approach to measure the phase and group velocity dispersion of Rayleigh wave component of Green's functions. The traveltime information derived from the dispersion is then used in a nonlinear tomographic approach to map the velocity perturbation of the region. The forward problem for the tomographic imaging can accurately track the evolution of a wavefront in highly heterogeneous media. Therefore the highly complex velocity distribution of the region is accurately reflected into the forward calculations used in the inversion. In general, accretionary prisms in the region are marked with quite low group and phase velocities with perturbations up to 50%. Active volcanoes in Sumatra and Java islands are also marked with low velocities. Rajang delta in north-west Kalimantan and thick sediments in South China Sea are imaged with low velocities.

Deciphering complex, functional structures with synchrotron-based absorption and phase contrast tomographic microscopy

NASA Astrophysics Data System (ADS)

Stampanoni, M.; Reichold, J.; Weber, B.; Haberthür, D.; Schittny, J.; Eller, J.; Büchi, F. N.; Marone, F.

2010-09-01

Nowadays, thanks to the high brilliance available at modern, third generation synchrotron facilities and recent developments in detector technology, it is possible to record volumetric information at the micrometer scale within few minutes. High signal-to-noise ratio, quantitative information on very complex structures like the brain micro vessel architecture, lung airways or fuel cells can be obtained thanks to the combination of dedicated sample preparation protocols, in-situ acquisition schemes and cutting-edge imaging analysis instruments. In this work we report on recent experiments carried out at the TOMCAT beamline of the Swiss Light Source [1] where synchrotron-based tomographic microscopy has been successfully used to obtain fundamental information on preliminary models for cerebral fluid flow [2], to provide an accurate mesh for 3D finite-element simulation of the alveolar structure of the pulmonary acinus [3] and to investigate the complex functional mechanism of fuel cells [4]. Further, we introduce preliminary results on the combination of absorption and phase contrast microscopy for the visualization of high-Z nanoparticles in soft tissues, a fundamental information when designing modern drug delivery systems [5]. As an outlook we briefly discuss the new possibilities offered by high sensitivity, high resolution grating interferomtery as well as Zernike Phase contrast nanotomography [6].

Labeling RNAs in Live Cells Using Malachite Green Aptamer Scaffolds as Fluorescent Probes.

PubMed

Yerramilli, V Siddartha; Kim, Kyung Hyuk

2018-03-16

RNAs mediate many different processes that are central to cellular function. The ability to quantify or image RNAs in live cells is very useful in elucidating such functions of RNA. RNA aptamer-fluorogen systems have been increasingly used in labeling RNAs in live cells. Here, we use the malachite green aptamer (MGA), an RNA aptamer that can specifically bind to malachite green (MG) dye and induces it to emit far-red fluorescence signals. Previous studies on MGA showed a potential for the use of MGA for genetically tagging other RNA molecules in live cells. However, these studies also exhibited low fluorescence signals and high background noise. Here we constructed and tested RNA scaffolds containing multiple tandem repeats of MGA as a strategy to increase the brightness of the MGA aptamer-fluorogen system as well as to make the system fluoresce when tagging various RNA molecules, in live cells. We demonstrate that our MGA scaffolds can induce fluorescence signals by up to ∼20-fold compared to the basal level as a genetic tag for other RNA molecules. We also show that our scaffolds function reliably as genetically encoded fluorescent tags for mRNAs of fluorescent proteins and other RNA aptamers.

Cytidine-stabilized gold nanocluster as a fluorescence turn-on and turn-off probe for dual functional detection of Ag(+) and Hg(2+).

PubMed

Zhang, Yuanyuan; Jiang, Hui; Wang, Xuemei

2015-04-22

In this study, we have developed a label-free, dual functional detection strategy for highly selective and sensitive determination of aqueous Ag(+) and Hg(2+) by using cytidine stabilized Au NCs and AuAg NCs as fluorescent turn-on and turn off probes, respectively. The Au NCs and AuAg NCs showed a remarkably rapid response and high selectivity for Ag(+) and Hg(2+) over other metal ions, and relevant detection limit of Ag(+) and Hg(2+) is ca. 10 nM and 30 nM, respectively. Importantly, the fluorescence enhanced Au NCs by doping Ag(+) can be conveniently reusable for the detection of Hg(2+) based on the corresponding fluorescence quenching. The sensing mechanism was based on the high-affinity metallophilic Hg(2+)-Ag(+) interaction, which effectively quenched the fluorescence of AuAg NCs. Furthermore, these fluorescent nanoprobes could be readily applied to Ag(+) and Hg(2+) detection in environmental water samples, indicating their possibility to be utilized as a convenient, dual functional, rapid response, and label-free fluorescence sensor for related environmental and health monitoring. Copyright © 2015 Elsevier B.V. All rights reserved.

A high-throughput system for high-quality tomographic reconstruction of large datasets at Diamond Light Source

PubMed Central

Atwood, Robert C.; Bodey, Andrew J.; Price, Stephen W. T.; Basham, Mark; Drakopoulos, Michael

2015-01-01

Tomographic datasets collected at synchrotrons are becoming very large and complex, and, therefore, need to be managed efficiently. Raw images may have high pixel counts, and each pixel can be multidimensional and associated with additional data such as those derived from spectroscopy. In time-resolved studies, hundreds of tomographic datasets can be collected in sequence, yielding terabytes of data. Users of tomographic beamlines are drawn from various scientific disciplines, and many are keen to use tomographic reconstruction software that does not require a deep understanding of reconstruction principles. We have developed Savu, a reconstruction pipeline that enables users to rapidly reconstruct data to consistently create high-quality results. Savu is designed to work in an ‘orthogonal’ fashion, meaning that data can be converted between projection and sinogram space throughout the processing workflow as required. The Savu pipeline is modular and allows processing strategies to be optimized for users' purposes. In addition to the reconstruction algorithms themselves, it can include modules for identification of experimental problems, artefact correction, general image processing and data quality assessment. Savu is open source, open licensed and ‘facility-independent’: it can run on standard cluster infrastructure at any institution. PMID:25939626

Tomographic inversion of satellite photometry. II

NASA Technical Reports Server (NTRS)

Solomon, S. C.; Hays, P. B.; Abreu, V. J.

1985-01-01

A method for combining nadir observations of emission features in the upper atmosphere with the result of a tomographic inversion of limb brightness measurements is presented. Simulated and actual results are provided, and error sensitivity is investigated.

Why do aged fluorescent tubes flicker?

NASA Astrophysics Data System (ADS)

Plihon, Nicolas; Ferrand, Jérémy; Guyomar, Tristan; Museur, Flavien; Taberlet, Nicolas

2017-11-01

Our everyday experience of aged and defective fluorescent tubes or bulbs informs us that they may flicker and emit a clicking sound while struggling to light up. In this article, the physical mechanisms controlling the initial illumination of a functioning fluorescent tube are investigated using a simple and affordable experimental setup. Thermionic emission from the electrodes of the tube controls the startup of fluorescent tubes. The origin of the faulty startup of aged fluorescent tubes is discussed and flickering regimes using functional tubes are artificially produced using a dedicated setup that decreases electron emission by the thermionic effect in a controlled manner. The physical parameters controlling the occurrence of flickering light are discussed, and their temporal statistics are reported.

Toward regional-scale adjoint tomography in the deep earth

NASA Astrophysics Data System (ADS)

Masson, Y.; Romanowicz, B. A.

2013-12-01

Thanks to the development of efficient numerical computation methods, such as the Spectral Element Method (SEM) and to the increasing power of computer clusters, it is now possible to obtain regional-scale images of the Earth's interior using adjoint-tomography (e.g. Tape, C., et al., 2009). As for now, these tomographic models are limited to the upper layers of the earth, i.e., they provide us with high-resolution images of the crust and the upper part of the mantle. Given the gigantic amount of calculation it represents, obtaing similar models at the global scale (i.e. images of the entire Earth) seems out of reach at the moment. Furthermore, it's likely that the first generation of such global adjoint tomographic models will have a resolution significantly smaller than the current regional models. In order to image regions of interests in the deep Earth, such as plumes, slabs or large low shear velocity provinces (LLSVPs), while keeping the computation tractable, we are developing new tools that will allow us to perform regional-scale adjoint-tomography at arbitrary depths. In a recent study (Masson et al., 2013), we showed that a numerical equivalent of the time reversal mirrors used in experimental acoustics permits to confine the wave propagation computations (i.e. using SEM simulations) inside the region to be imaged. With this ability to limit wave propagation modeling inside a region of interest, obtaining the adjoint sensitivity kernels needed for tomographic imaging is only two steps further. First, the local wavefield modeling needs to be coupled with field extrapolation techniques in order to obtain synthetic seismograms at the surface of the earth. These seismograms will account for the 3D structure inside the region of interest in a quasi-exact manner. We will present preliminary results where the field-extrapolation is performed using Green's function computed in a 1D Earth model thanks to the Direct Solution Method (DSM). Once synthetic seismograms can be obtained, it is possible to evaluate the misfit between observed and computed seismograms. The second step will then be to extrapolate the misfit function back into the SEM region in order to compute local adjoint sensitivity kernels. When available, these kernels will allow us to perform regional-scale adjoint tomography at arbitrary locations inside the earth. Masson Y., Cupillard P., Capdeville Y., & Romanowicz B., 2013. On the numerical implementation of time-reversal mirrors for tomographic imaging, Journal of Geophysical Research (under review). Tape, C., et al. (2009). "Adjoint tomography of the southern California crust." Science 325(5943): 988-992.

Polycapillary based μXRF station for 3D colour tomography

NASA Astrophysics Data System (ADS)

Hampai, D.; Cherepennikov, Yu. M.; Liedl, A.; Cappuccio, G.; Capitolo, E.; Iannarelli, M.; Azzutti, C.; Gladkikh, Yu. P.; Marcelli, A.; Dabagov, S. B.

2018-04-01

The "Rainbow X-Ray" (RXR) experimental station at XLab Frascati of the Frascati's National Laboratories (LNF) INFN is a dedicated station for X-ray fluorescence studies based on the use of polycapillary lenses in a confocal geometry. The flexible RXR layout allows investigating specimens of the dimensions ranging from several millimeters up to half meter and weighting up to several tens of kilograms. Compared to similar existing XRF stations, apart of the possibility for investigating large samples, the main advantage of this equipment is the detection system with two spectrometers optimized to work separately at high and at low X-ray energies. The confocal geometry combined with a 3-axes fine motion system makes possible 3D μXRF elemental tomographic acquisitions (colour tomography). At present this station in operation at high XRF energies is used for cultural heritage and geological applications. We present and discuss here the analytical performances of this experimental station pointing out the advantages in different application areas.

Childhood-Onset Asthma in Smokers. Association between CT Measures of Airway Size, Lung Function, and Chronic Airflow Obstruction

PubMed Central

Hardin, Megan E.; Come, Carolyn E.; San José Estépar, Raúl; Ross, James C.; Kurugol, Sila; Okajima, Yuka; Han, MeiLan K.; Kim, Victor; Ramsdell, Joe; Silverman, Edwin K.; Crapo, James D.; Lynch, David A.; Make, Barry; Barr, R. Graham; Hersh, Craig P.; Washko, George R.

2014-01-01

Rationale and Objectives: Asthma is associated with chronic airflow obstruction. Our goal was to assess the association of computed tomographic measures of airway wall volume and lumen volume with the FEV1 and chronic airflow obstruction in smokers with childhood-onset asthma. Methods: We analyzed clinical, lung function, and volumetric computed tomographic airway volume data from 7,266 smokers, including 590 with childhood-onset asthma. Small wall volume and small lumen volume of segmental airways were defined as measures 1 SD below the mean. We assessed the association between small wall volume, small lumen volume, FEV1, and chronic airflow obstruction (post-bronchodilator FEV1/FVC ratio < 0.7) using linear and logistic models. Measurements and Main Results: Compared with subjects without childhood-onset asthma, those with childhood-onset asthma had smaller wall volume and lumen volume (P < 0.0001) of segmental airways. Among subjects with childhood-onset asthma, those with the smallest wall volume and lumen volume had the lowest FEV1 and greatest odds of chronic airflow obstruction. A similar tendency was seen in those without childhood-onset asthma. When comparing these two groups, both small wall volume and small lumen volume were more strongly associated with FEV1 and chronic airflow obstruction among subjects with childhood-asthma in multivariate models. Conclusion: In smokers with childhood-onset asthma, smaller airways are associated with reduced lung function and chronic airflow obstruction. Clinical trial registered with www.clinicaltrials.gov (NCT00608764). PMID:25296268

Childhood-onset asthma in smokers. association between CT measures of airway size, lung function, and chronic airflow obstruction.

PubMed

Diaz, Alejandro A; Hardin, Megan E; Come, Carolyn E; San José Estépar, Raúl; Ross, James C; Kurugol, Sila; Okajima, Yuka; Han, MeiLan K; Kim, Victor; Ramsdell, Joe; Silverman, Edwin K; Crapo, James D; Lynch, David A; Make, Barry; Barr, R Graham; Hersh, Craig P; Washko, George R

2014-11-01

Asthma is associated with chronic airflow obstruction. Our goal was to assess the association of computed tomographic measures of airway wall volume and lumen volume with the FEV1 and chronic airflow obstruction in smokers with childhood-onset asthma. We analyzed clinical, lung function, and volumetric computed tomographic airway volume data from 7,266 smokers, including 590 with childhood-onset asthma. Small wall volume and small lumen volume of segmental airways were defined as measures 1 SD below the mean. We assessed the association between small wall volume, small lumen volume, FEV1, and chronic airflow obstruction (post-bronchodilator FEV1/FVC ratio < 0.7) using linear and logistic models. Compared with subjects without childhood-onset asthma, those with childhood-onset asthma had smaller wall volume and lumen volume (P < 0.0001) of segmental airways. Among subjects with childhood-onset asthma, those with the smallest wall volume and lumen volume had the lowest FEV1 and greatest odds of chronic airflow obstruction. A similar tendency was seen in those without childhood-onset asthma. When comparing these two groups, both small wall volume and small lumen volume were more strongly associated with FEV1 and chronic airflow obstruction among subjects with childhood-asthma in multivariate models. In smokers with childhood-onset asthma, smaller airways are associated with reduced lung function and chronic airflow obstruction. Clinical trial registered with www.clinicaltrials.gov (NCT00608764).

Lung Mass in Smokers.

PubMed

Washko, George R; Kinney, Gregory L; Ross, James C; San José Estépar, Raúl; Han, MeiLan K; Dransfield, Mark T; Kim, Victor; Hatabu, Hiroto; Come, Carolyn E; Bowler, Russell P; Silverman, Edwin K; Crapo, James; Lynch, David A; Hokanson, John; Diaz, Alejandro A

2017-04-01

Emphysema is characterized by airspace dilation, inflammation, and irregular deposition of elastin and collagen in the interstitium. Computed tomographic studies have reported that lung mass (LM) may be increased in smokers, a finding attributed to inflammatory and parenchymal remodeling processes observed on histopathology. We sought to examine the epidemiologic and clinical associations of LM in smokers. Baseline epidemiologic, clinical, and computed tomography (CT) data (n = 8156) from smokers enrolled into the COPDGene Study were analyzed. LM was calculated from the CT scan. Changes in lung function at 5 years' follow-up were available from 1623 subjects. Regression analysis was performed to assess for associations of LM with forced expiratory volume in 1 second (FEV 1 ) and FEV 1 decline. Subjects with Global Initiative for Chronic Obstructive Lung Disease (GOLD) 1 chronic obstructive pulmonary disease had greater LM than either smokers with normal lung function or those with GOLD 2-4 chronic obstructive pulmonary disease (P < 0.001 for both comparisons). LM was predictive of the rate of the decline in FEV 1 (decline per 100 g, -4.7 ± 1.7 mL/y, P = 0.006). Our cross-sectional data suggest the presence of a biphasic radiological remodeling process in smokers: the presence of such nonlinearity must be accounted for in longitudinal computed tomographic studies. Baseline LM predicts the decline in lung function. Copyright © 2017 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

Efficient control schemes with limited computation complexity for Tomographic AO systems on VLTs and ELTs

NASA Astrophysics Data System (ADS)

Petit, C.; Le Louarn, M.; Fusco, T.; Madec, P.-Y.

2011-09-01

Various tomographic control solutions have been proposed during the last decades to ensure efficient or even optimal closed-loop correction to tomographic Adaptive Optics (AO) concepts such as Laser Tomographic AO (LTAO), Multi-Conjugate AO (MCAO). The optimal solution, based on Linear Quadratic Gaussian (LQG) approach, as well as suboptimal but efficient solutions such as Pseudo-Open Loop Control (POLC) require multiple Matrix Vector Multiplications (MVM). Disregarding their respective performance, these efficient control solutions thus exhibit strong increase of on-line complexity and their implementation may become difficult in demanding cases. Among them, two cases are of particular interest. First, the system Real-Time Computer architecture and implementation is derived from past or present solutions and does not support multiple MVM. This is the case of the AO Facility which RTC architecture is derived from the SPARTA platform and inherits its simple MVM architecture, which does not fit with LTAO control solutions for instance. Second, considering future systems such as Extremely Large Telescopes, the number of degrees of freedom is twenty to one hundred times bigger than present systems. In these conditions, tomographic control solutions can hardly be used in their standard form and optimized implementation shall be considered. Single MVM tomographic control solutions represent a potential solution, and straightforward solutions such as Virtual Deformable Mirrors have been already proposed for LTAO but with tuning issues. We investigate in this paper the possibility to derive from tomographic control solutions, such as POLC or LQG, simplified control solutions ensuring simple MVM architecture and that could be thus implemented on nowadays systems or future complex systems. We theoretically derive various solutions and analyze their respective performance on various systems thanks to numerical simulation. We discuss the optimization of their performance and stability issues with respect to classic control solutions. We finally discuss off-line computation and implementation constraints.

Dextran sulfate sodium-induced acute colitis impairs dermal lymphatic function in mice.

PubMed

Agollah, Germaine D; Wu, Grace; Peng, Ho-Lan; Kwon, Sunkuk

2015-12-07

To investigate whether dermal lymphatic function and architecture are systemically altered in dextran sulfate sodium (DSS)-induced acute colitis. Balb/c mice were administered 4% DSS in lieu of drinking water ad libitum for 7 d and monitored to assess disease activity including body weight, diarrhea severity, and fecal bleeding. Control mice received standard drinking water with no DSS. Changes in mesenteric lymphatics were assessed following oral administration of a fluorescently-labelled fatty acid analogue, while dermal lymphatic function and architecture was longitudinally characterized using dynamic near-infrared fluorescence (NIRF) imaging following intradermal injection of indocyanine green (ICG) at the base of the tail or to the dorsal aspect of the left paw prior to, 4, and 7 d after DSS administration. We also measured dye clearance rate after injection of Alexa680-bovine serum albumin (BSA). NIRF imaging data was analyzed to reveal lymphatic contractile activity after selecting fixed regions of interest (ROIs) of the same size in fluorescent lymphatic vessels on fluorescence images. The averaged fluorescence intensity within the ROI of each fluorescence image was plotted as a function of imaging time and the lymphatic contraction frequency was computed by assessing the number of fluorescent pulses arriving at a ROI. Mice treated with DSS developed acute inflammation with clinical symptoms of loss of body weight, loose feces/watery diarrhea, and fecal blood, all of which were aggravated as disease progressed to 7 d. Histological examination of colons of DSS-treated mice confirmed acute inflammation, characterized by segmental to complete loss of colonic mucosa with an associated chronic inflammatory cell infiltrate that extended into the deeper layers of the wall of the colon, compared to control mice. In situ intravital imaging revealed that mice with acute colitis showed significantly fewer fluorescent mesenteric lymphatic vessels, indicating impaired uptake of a lipid tracer within mesenteric lymphatics. Our in vivo NIRF imaging data demonstrated dilated dermal lymphatic vessels, which were confirmed by immunohistochemical staining of lymphatic vessels, and significantly reduced lymphatic contractile function in the skin of mice with DSS-induced acute colitis. Quantification of the fluorescent intensity remaining in the depot as a function of time showed that there was significantly higher Alexa680-BSA fluorescence in mice with DSS-induced acute colitis compared to pre-treatment with DSS, indicative of impaired lymphatic drainage. The lymphatics are locally and systemically altered in acute colitis, and functional NIRF imaging is useful for noninvasively monitoring systemic lymphatic changes during inflammation.

Assessing the resolution-dependent utility of tomograms for geostatistics

USGS Publications Warehouse

Day-Lewis, F. D.; Lane, J.W.

2004-01-01

Geophysical tomograms are used increasingly as auxiliary data for geostatistical modeling of aquifer and reservoir properties. The correlation between tomographic estimates and hydrogeologic properties is commonly based on laboratory measurements, co-located measurements at boreholes, or petrophysical models. The inferred correlation is assumed uniform throughout the interwell region; however, tomographic resolution varies spatially due to acquisition geometry, regularization, data error, and the physics underlying the geophysical measurements. Blurring and inversion artifacts are expected in regions traversed by few or only low-angle raypaths. In the context of radar traveltime tomography, we derive analytical models for (1) the variance of tomographic estimates, (2) the spatially variable correlation with a hydrologic parameter of interest, and (3) the spatial covariance of tomographic estimates. Synthetic examples demonstrate that tomograms of qualitative value may have limited utility for geostatistics; moreover, the imprint of regularization may preclude inference of meaningful spatial statistics from tomograms.

Subsurface PpIX imaging in vivo with ultrasound-guided tomographic spectroscopy: reconstruction vs. born-normalized data

NASA Astrophysics Data System (ADS)

Flynn, Brendan P.; D'Souza, Alisha V.; Kanick, Stephen C.; Maytin, Edward; Hasan, Tayyaba; Pogue, Brian W.

2013-03-01

Aminolevulinic acid (ALA)-induced Protoporphyrin IX (PpIX)-based photodynamic therapy (PDT) is an effective treatment for skin cancers including basal cell carcinoma (BCC). Topically applied ALA promotes PpIX production preferentially in tumors, and many strategies have been developed to increase PpIX distribution and PDT treatment efficacy at depths > 1mm is not fully understood. While surface imaging techniques provide useful diagnosis, dosimetry, and efficacy information for superficial tumors, these methods cannot interrogate deeper tumors to provide in situ insight into spatial PpIX distributions. We have developed an ultrasound-guided, white-light-informed, tomographics spectroscopy system for the spatial measurement of subsurface PpIX. Detailed imaging system specifications, methodology, and optical-phantom-based characterization will be presented separately. Here we evaluate preliminary in vivo results using both full tomographic reconstruction and by plotting individual tomographic source-detector pair data against US images.

Synthesis of di-functional ligand and fluorescently labeling SiO2 microspheres

NASA Astrophysics Data System (ADS)

Chen, Kexu; Kang, Ming; Liu, Min; Shen, Simin; Sun, Rong

2018-05-01

In order to complete the fluorescent labeling of SiO2 microspheres, a kind of di-functional ligand was synthesized and purified, which could not only coordinate rare earth ions but also react with the active groups to bond host materials with an alkoxysilane groups. Fourier transform infrared spectroscopy (FT-IR), 1H NMR spectra, MS spectra, field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and luminescence spectrophotometer were used to study the structure of di-functional ligand and properties of fluorescent coupling agent and fluorescent labeled SiO2 microspheres. The optimal experiment conditions were acquired as follows: molar ratio as 1: 4 (MDBM: MICPTES), reaction time at 6 h and reaction temperature as 65 °C (yield up to 40%) through the orthogonal experiment and purification process. The results indicated that fluorescent coupling agent presented red photoluminesence of Eu3+ ions at 610 nm, and the absolute quantum yield was 11%. On the other hand, the hydrolysis of the coupling agent reacted on the surface of SiO2 microspheres and presented fluorescent labeling homogeneously.

Preparation of Yellow-Green-Emissive Carbon Dots and Their Application in Constructing a Fluorescent Turn-On Nanoprobe for Imaging of Selenol in Living Cells.

PubMed

Wang, Qin; Zhang, Shengrui; Zhong, Yaogang; Yang, Xiao-Feng; Li, Zheng; Li, Hua

2017-02-07

Selenocysteine (Sec) carries out the majority of the functions of the various Se-containing species in vivo. Thus, it is of great importance to develop sensitive and selective assays to detect Sec. Herein, a carbon-dot-based fluorescent turn-on probe for highly selective detection of selenol in living cells is presented. The highly photoluminescent carbon dots that emit yellow-green fluorescence (Y-G-CDs; λ max = 520 nm in water) were prepared by using m-aminophenol as carbon precursor through a facile solvothermal method. The surface of Y-G-CDs was then covalently functionalized with 2,4-dinitrobenzenesulfonyl chloride (DNS-Cl) to afford the 2,4-dinitrobenzene-functionalized CDs (CD-DNS) as a nanoprobe for selenol. CD-DNS is almost nonfluorescent. However, upon treating with Sec, the DNS moiety of CD-DNS can be readily cleaved by selenolate through a nucleophilic substitution process, resulting in the formation of highly fluorescent Y-G-CDs and hence leads to a dramatic increase in fluorescence intensity. The proposed nanoprobe exhibits high sensitivity and selectivity toward Sec over biothiols and other biological species. A preliminary study shows that CD-DNS can function as a useful tool for fluorescence imaging of exogenous and endogenous selenol in living cells.

Interaction of amino acid-functionalized silver nanoparticles and Candida albicans polymorphs: A deep-UV fluorescence imaging study.

PubMed

Dojčilović, Radovan; Pajović, Jelena D; Božanić, Dušan K; Bogdanović, Una; Vodnik, Vesna V; Dimitrijević-Branković, Suzana; Miljković, Miona G; Kaščaková, Slavka; Réfrégiers, Matthieu; Djoković, Vladimir

2017-07-01

The interaction of the tryptophan functionalized Ag nanoparticles and live Candida albicans cells was studied by synchrotron excitation deep-ultraviolet (DUV) fluorescence imaging at the DISCO beamline of Synchrotron SOLEIL. DUV imaging showed that incubation of the fungus with functionalized nanoparticles results in significant increase in the fluorescence signal. The analysis of the images revealed that the interaction of the nanoparticles with (pseudo)hyphae polymorphs of the diploid fungus was less pronounced than in the case of yeast cells or budding spores. The changes in the intensity of the fluorescence signals of the cells after incubation were followed in [327-353nm] and [370-410nm] spectral ranges that correspond to the fluorescence of tryptophan in non-polar and polar environment, respectively. As a consequence of the environmental sensitivity of the silver-tryptophan fluorescent nanoprobe, we were able to determine the possible accumulation sites of the nanoparticles. The analysis of the intensity decay kinetics showed that the photobleaching effects were more pronounced in the case of the functionalized nanoparticle treated cells. The results of time-integrated emission in the mentioned spectral ranges suggested that the nanoparticles penetrate the cells, but that the majority of the nanoparticles attach to the cells' surfaces. Copyright © 2017 Elsevier B.V. All rights reserved.

Unusual Fluorescent Responses of Morpholine-functionalized Fluorescent Probes to pH via Manipulation of BODIPY’s HOMO and LUMO Energy Orbitals for Intracellular pH Detection

PubMed Central

Zhang, Jingtuo; Yang, Mu; Mazi, Wafa; Adhikari, Kapil; Fang, Mingxi; Xie, Fei; Valenzano, Loredana; Tiwari, Ashutosh; Luo, Fen-Tair; Liu, Haiying

2016-01-01

Three uncommon morpholine-based fluorescent probes (A, B and C) for pH were prepared by introducing morpholine residues to BODIPY dyes at 4,4’- and 2,6-positions, respectively. In contrast to morpholine-based fluorescent probes for pH reported in literature, these fluorescent probes display high fluorescence in a basic condition while they exhibit very weak fluorescence in an acidic condition. The theoretical calculation confirmed that morpholine is unable to function as either an electron donor or an electron acceptor to quench the BODIPY fluorescence in the neutral and basic condition via photo-induced electron transfer (PET) mechanism because the LUMO energy of morpholine is higher than those of the BODIPY dyes while its HOMO energy is lower than those of the BODIPY dyes. However, the protonation of tertiary amines of the morpholine residues in an acidic environment leads to fluorescence quenching of the BODIPY dyes via d-PET mechanism. The fluorescence quenching is because the protonation effectively decreases the LUMO energy which locates between the HOMO and LUMO energies of the BODIPY dyes. Fluorescent probe C with deep-red emission has been successfully used to detect pH changes in mammalian cells. PMID:27547822

Indocyanine green fluorescence angiography for quantitative evaluation of in situ parathyroid gland perfusion and function after total thyroidectomy.

PubMed

Lang, Brian Hung-Hin; Wong, Carlos K H; Hung, Hing Tsun; Wong, Kai Pun; Mak, Ka Lun; Au, Kin Bun

2017-01-01

Because the fluorescent light intensity on an indocyanine green fluorescence angiography reflects the blood perfusion within a focused area, the fluorescent light intensity in the remaining in situ parathyroid glands may predict postoperative hypocalcemia risk after total thyroidectomy. Seventy patients underwent intraoperative indocyanine green fluorescence angiography after total thyroidectomy. Any parathyroid glands with a vascular pedicle was left in situ while any parathyroid glands without pedicle or inadvertently removed was autotransplanted. After total thyroidectomy, an intravenous 2.5 mg indocyanine green fluorescence angiography was given and real-time fluorescent images of the thyroid bed were recorded using the SPY imaging system (Novadaq, Ontario, Canada). The fluorescent light intensity of each indocyanine green fluorescence angiography as well as the average and greatest fluorescent light intensity in each patient were calculated. Postoperative hypocalcemia was defined as adjusted calcium <2.00 mmol/L within 24 hours. The fluorescent light intensity between discolored and normal-looking indocyanine green fluorescence angiographies was similar (P = .479). No patients with a greatest fluorescent light intensity >150% developed postoperative hypocalcemia while 9 (81.8%) patients with a greatest fluorescent light intensity ≤150% did. Similarly, no patients with an average fluorescent light intensity >109% developed PH while 9 (30%) with an average fluorescent light intensity ≤109% did. The greatest fluorescent light intensity was more predictive than day-0 postoperative hypocalcemia (P = .027) and % PTH drop day-0 to 1 (P < .001). Indocyanine green fluorescence angiography is a promising operative adjunct in determining residual parathyroid glands function and predicting postoperative hypocalcemia risk after total thyroidectomy. Copyright © 2016 Elsevier Inc. All rights reserved.

Fluorescence quantum yield measurements of fluorescent proteins: a laboratory experiment for a biochemistry or molecular biophysics laboratory course.

PubMed

Wall, Kathryn P; Dillon, Rebecca; Knowles, Michelle K

2015-01-01

Fluorescent proteins are commonly used in cell biology to assess where proteins are within a cell as a function of time and provide insight into intracellular protein function. However, the usefulness of a fluorescent protein depends directly on the quantum yield. The quantum yield relates the efficiency at which a fluorescent molecule converts absorbed photons into emitted photons and it is necessary to know for assessing what fluorescent protein is the most appropriate for a particular application. In this work, we have designed an upper-level, biochemistry laboratory experiment where students measure the fluorescence quantum yields of fluorescent proteins relative to a standard organic dye. Four fluorescent protein variants, enhanced cyan fluorescent protein (ECFP), enhanced green fluorescent protein (EGFP), mCitrine, and mCherry, were used, however the methods described are useful for the characterization of any fluorescent protein or could be expanded to fluorescent quantum yield measurements of organic dye molecules. The laboratory is designed as a guided inquiry project and takes two, 4 hr laboratory periods. During the first day students design the experiment by selecting the excitation wavelength, choosing the standard, and determining the concentration needed for the quantum yield experiment that takes place in the second laboratory period. Overall, this laboratory provides students with a guided inquiry learning experience and introduces concepts of fluorescence biophysics into a biochemistry laboratory curriculum. © 2014 The International Union of Biochemistry and Molecular Biology.

One-step fabrication of PEGylated fluorescent nanodiamonds through the thiol-ene click reaction and their potential for biological imaging

NASA Astrophysics Data System (ADS)

Huang, Hongye; Liu, Meiying; Tuo, Xun; Chen, Junyu; Mao, Liucheng; Wen, Yuanqing; Tian, Jianwen; Zhou, Naigen; Zhang, Xiaoyong; Wei, Yen

2018-05-01

Over the past years, fluorescent carbon nanoparticles have got growing interest for biological imaging. Fluorescent nanodiamonds (FNDs) are novel fluorescent carbon nanoparticles with multitudinous useful properties, including remarkable fluorescence properties, extremely low toxicity and high refractive index. However, facile preparation of FNDs with designable properties and functions from non-fluorescent detonation nanodiamonds (DNDs) has demonstrated to be challengeable. In this work, we reported for the first time that preparation of Polyethylene glycol (PEG) functionalized FNDs through a one-step thiol-ene click reaction using thiol containing PEG (PEG-SH) as the coating agent. Based on the characterization results, we demonstrated that PEG-SH could be efficiently introduced on DNDs to obtain FNDs through the thiol-ene click chemistry. The resultant FND-PEG composites showed high water dispersibility, strong fluorescence and low cytotoxicity. Moreover, FND-PEG composites could be internalized by cells and displayed good cell dyeing performance. All of these features implied that FND-PEG composites are of great potential for biological imaging. Taken together, a facile one-step strategy based on the one-step thiol-ene click reaction has been developed for efficient preparation of FND-PEG composites from non-fluorescent DNDs. The strategy should be also useful for fabrication of many other functional FNDs via using different thiol containing compounds for the universality of thiol-ene click reaction.

Multimodal Light Microscopy Approaches to Reveal Structural and Functional Properties of Promyelocytic Leukemia Nuclear Bodies.

PubMed

Hoischen, Christian; Monajembashi, Shamci; Weisshart, Klaus; Hemmerich, Peter

2018-01-01

The promyelocytic leukemia ( pml ) gene product PML is a tumor suppressor localized mainly in the nucleus of mammalian cells. In the cell nucleus, PML seeds the formation of macromolecular multiprotein complexes, known as PML nuclear bodies (PML NBs). While PML NBs have been implicated in many cellular functions including cell cycle regulation, survival and apoptosis their role as signaling hubs along major genome maintenance pathways emerged more clearly. However, despite extensive research over the past decades, the precise biochemical function of PML in these pathways is still elusive. It remains a big challenge to unify all the different previously suggested cellular functions of PML NBs into one mechanistic model. With the advent of genetically encoded fluorescent proteins it became possible to trace protein function in living specimens. In parallel, a variety of fluorescence fluctuation microscopy (FFM) approaches have been developed which allow precise determination of the biophysical and interaction properties of cellular factors at the single molecule level in living cells. In this report, we summarize the current knowledge on PML nuclear bodies and describe several fluorescence imaging, manipulation, FFM, and super-resolution techniques suitable to analyze PML body assembly and function. These include fluorescence redistribution after photobleaching, fluorescence resonance energy transfer, fluorescence correlation spectroscopy, raster image correlation spectroscopy, ultraviolet laser microbeam-induced DNA damage, erythrocyte-mediated force application, and super-resolution microscopy approaches. Since most if not all of the microscopic equipment to perform these techniques may be available in an institutional or nearby facility, we hope to encourage more researches to exploit sophisticated imaging tools for their research in cancer biology.

Unraveling the Origin of the Bermuda Rise Using Receiver Functions: Insights from Mantle Discontinuity Structure

NASA Astrophysics Data System (ADS)

Burky, A.; Irving, J. C. E.; Simons, F.

2017-12-01

The Bermuda Rise is an enigmatic intraplate bathymetric feature which is considered a candidate hotspot in some catalogs, but remains a poor candidate due to the lack of an associated seamount chain and the absence of any present-day volcanism. Tomographic models of the seismic P and S wave velocity structure in the upper mantle and transition zone beneath Bermuda and the surrounding seafloor consistently resolve low velocity structures, but the magnitude, lateral dimensions, and position of these low velocity structures vary considerably between models. Due to these discrepancies, it remains difficult to attribute the observed velocity anomalies to thermal or chemical heterogeneity in this region. In addition to tomographic modeling, previous studies investigated the mantle transition zone structure beneath Bermuda by calculating receiver functions for GSN station BBSR, and suggested thinning of the transition zone as well as depressed discontinuity topography. In this study, we expand upon those studies by including the wealth of newly available data, and by incorporating a suite of three-dimensional velocity models. We calculate radial receiver functions in multiple frequency bands for the highest quality seismograms selected from over 5,000 waveforms recorded at station BBSR between October 2008 and August 2017 using the iterative deconvolution technique. We use various one- and three-dimensional velocity models to depth-convert our receiver functions to find the depths of the mantle transition zone discontinuities responsible for the signals in our receiver functions. The observed discontinuity topography is interpreted in the context of candidate mineralogical phase transitions and mantle temperature. To gain a more comprehensive understanding of our observations, we also calculate synthetic seismograms using AxiSEM, compute radial receiver functions for these synthetic data, and compare the results to the real receiver functions. Lastly, we discuss our results in the context of the geologic and geodynamic history of the Bermuda Rise.

Interrogating Surface Functional Group Heterogeneity of Activated Thermoplastics Using Super-Resolution Fluorescence Microscopy.

PubMed

ONeil, Colleen E; Jackson, Joshua M; Shim, Sang-Hee; Soper, Steven A

2016-04-05

We present a novel approach for characterizing surfaces utilizing super-resolution fluorescence microscopy with subdiffraction limit spatial resolution. Thermoplastic surfaces were activated by UV/O3 or O2 plasma treatment under various conditions to generate pendant surface-confined carboxylic acids (-COOH). These surface functional groups were then labeled with a photoswitchable dye and interrogated using single-molecule, localization-based, super-resolution fluorescence microscopy to elucidate the surface heterogeneity of these functional groups across the activated surface. Data indicated nonuniform distributions of these functional groups for both COC and PMMA thermoplastics with the degree of heterogeneity being dose dependent. In addition, COC demonstrated relative higher surface density of functional groups compared to PMMA for both UV/O3 and O2 plasma treatment. The spatial distribution of -COOH groups secured from super-resolution imaging were used to simulate nonuniform patterns of electroosmotic flow in thermoplastic nanochannels. Simulations were compared to single-particle tracking of fluorescent nanoparticles within thermoplastic nanoslits to demonstrate the effects of surface functional group heterogeneity on the electrokinetic transport process.

Assessment of Severity of Ovine Smoke Inhalation Injury by Analysis of Computed Tomographic Scans

DTIC Science & Technology

2003-09-01

Computerized analysis of three- dimensional reconstructed scans was also performed, based on Hounsfield unit ranges: hyperinflated, 1,000 to 900; normal...the interactive segmentation function of the software. The pulmonary parenchyma was separated into four regions based on the Hounsfield unit (HU...SII) severity. Methods: Twenty anesthetized sheep underwent graded SII: group I, no smoke; group II, 5 smoke units ; group III, 10 units ; and group IV

[Development of fluorescent probes for bone imaging in vivo ~Fluorescent probes for intravital imaging of osteoclast activity~.

PubMed

Minoshima, Masafumi; Kikuchi, Kazuya

Fluorescent molecules are widely used as a tool to directly visualize target biomolecules in vivo. Fluorescent probes have the advantage that desired function can be rendered based on rational design. For bone-imaging fluorescent probes in vivo, they should be delivered to bone tissue upon administration. Recently, a fluorescent probe for detecting osteoclast activity was developed. The fluorescent probe has acid-sensitive fluorescence property, specific delivery to bone tissue, and durability against laser irradiation, which enabled real-time intravital imaging of bone-resorbing osteoclasts for a long period of time.

A halochromic stimuli-responsive reversible fluorescence switching 3, 4, 9, 10-perylene tetracarboxylic acid dye for fabricating rewritable platform

NASA Astrophysics Data System (ADS)

Hariharan, P. S.; Pitchaimani, J.; Madhu, Vedichi; Anthony, Savarimuthu Philip

2017-02-01

3, 4, 9, 10-perylene tetracarboxylic acid (PTCA), a strongly fluorescent water soluble dye with halochromic functionality showed pH dependent reversible fluorescence switching. The strong fluorescence of PTCA (Φf = 0.67) in basic medium was completely quenched upon acidification. The fluorescent PTCA has been transferred on to a solid substrate (filter paper and glass plate) that also showed reversible off-on fluorescence switching by acid/base and drying/water vapor exposure. The reversible fluorescence switching of PTCA could be of potential interest for fabricating rewritable fluorescent medium.

Optical imaging-guided cancer therapy with fluorescent nanoparticles

PubMed Central

Jiang, Shan; Gnanasammandhan, Muthu Kumara; Zhang, Yong

2010-01-01

The diagnosis and treatment of cancer have been greatly improved with the recent developments in nanotechnology. One of the promising nanoscale tools for cancer diagnosis is fluorescent nanoparticles (NPs), such as organic dye-doped NPs, quantum dots and upconversion NPs that enable highly sensitive optical imaging of cancer at cellular and animal level. Furthermore, the emerging development of novel multi-functional NPs, which can be conjugated with several functional molecules simultaneously including targeting moieties, therapeutic agents and imaging probes, provides new potentials for clinical therapies and diagnostics and undoubtedly will play a critical role in cancer therapy. In this article, we review the types and characteristics of fluorescent NPs, in vitro and in vivo imaging of cancer using fluorescent NPs and multi-functional NPs for imaging-guided cancer therapy. PMID:19759055

Distance-dependent Fluorescence Quenching and Binding of CdSe Quantum Dots by Functionalized Nitroxide Radicals

PubMed Central

Tansakul, Chittreeya; Lilie, Erin; Walter, Eric D.; Rivera, Frank; Wolcott, Abraham; Zhang, Jin Z.; Millhauser, Glenn L.

2010-01-01

Quantum dot (QD) fluorescence is effectively quenched at low concentration by nitroxides bearing amine or carboxylic acid ligands. The association constants and fluorescence quenching of CdSe QDs with these derivatized nitroxides have been examined using electron paramagnetic resonance (EPR) and fluorescence spectroscopy. The EPR spectra in the non-protic solvent toluene are extremely sensitive to intermolecular and intramolecular hydrogen bonding of the functionalized nitroxides. Fluorescence measurements show that quenching of QD luminescence is nonlinear, with a strong dependence on the distance between the radical and the QD. The quenched fluorescence is restored when the surface-bound nitroxides are converted to hydroxylamines by mild reducing agents, or trapped by carbon radicals to form alkoxyamines. EPR studies indicate that photoreduction of the nitroxide occurs in toluene solution upon photoexcitation at 365 nm. However, photolysis in benzene solution gives no photoreduction, suggesting that photoreduction in toluene is independent of the quenching mechanism. The fluorescence quenching of QDs by nitroxide binding is a reversible process. PMID:20473339

LIFDAR: A Diagnostic Tool for the Ionosphere

NASA Astrophysics Data System (ADS)

Kia, O. E.; Rodgers, C. T.; Batholomew, J. L.

2011-12-01

ITT Corporation proposes a novel system to measure and monitor the ion species within the Earth's ionosphere called Laser Induced Fluorescence Detection and Ranging (LIFDAR). Unlike current ionosphere measurements that detect electrons and magnetic field, LIFDAR remotely measures the major contributing ion species to the electron plasma. The LIFDAR dataset has the added capability to demonstrate stratification and classification of the layers of the ionosphere to ultimately give a true tomographic view. We propose a proof of concept study using existing atmospheric LIDAR sensors combined with a mountaintop observatory for a single ion species that is prevalent in all layers of the atmosphere. We envision the LIFDAR concept will enable verification, validation, and exploration of the physics of the magneto-hydrodynamic models used in ionosphere forecasting community. The LIFDAR dataset will provide the necessary ion and electron density data for the system wide data gap. To begin a proof of concept, we present the science justification of the LIFDAR system based on the model photon budget. This analysis is based on the fluorescence of ionized oxygen within the ionosphere versus altitude. We use existing model abundance data of the ionosphere during normal and perturbed states. We propagate the photon uncertainties from the laser source through the atmosphere to the plasma and back to the collecting optics and detector. We calculate the expected photon budget to determine signal to noise estimates based on the targeted altitude and detection efficiency. Finally, we use these results to derive a LIFDAR observation strategy compatible with operational parameters.

Total Face, Eyelids, Ears, Scalp, and Skeletal Subunit Transplant Research Procurement: A Translational Simulation Model.

PubMed

Sosin, Michael; Ceradini, Daniel J; Hazen, Alexes; Sweeney, Nicole G; Brecht, Lawrence E; Levine, Jamie P; Staffenberg, David A; Saadeh, Pierre B; Bernstein, G Leslie; Rodriguez, Eduardo D

2016-05-01

Cadaveric face transplant models are routinely used for technical allograft design, perfusion assessment, and transplant simulation but are associated with substantial limitations. The purpose of this study was to describe the experience of implementing a translational donor research facial procurement and solid organ allograft recovery model. Institutional review board approval was obtained, and a 49-year-old, brain-dead donor was identified for facial vascularized composite allograft research procurement. The family generously consented to donation of solid organs and the total face, eyelids, ears, scalp, and skeletal subunit allograft. The successful sequence of computed tomographic scanning, fabrication and postprocessing of patient-specific cutting guides, tracheostomy placement, preoperative fluorescent angiography, silicone mask facial impression, donor facial allograft recovery, postprocurement fluorescent angiography, and successful recovery of kidneys and liver occurred without any donor instability. Preservation of the bilateral external carotid arteries, facial arteries, occipital arteries, and bilateral thyrolinguofacial and internal jugular veins provided reliable and robust perfusion to the entirety of the allograft. Total time of facial procurement was 10 hours 57 minutes. Essential to clinical face transplant outcomes is the preparedness of the institution, multidisciplinary face transplant team, organ procurement organization, and solid organ transplant colleagues. A translational facial research procurement and solid organ recovery model serves as an educational experience to modify processes and address procedural, anatomical, and logistical concerns for institutions developing a clinical face transplantation program. This methodical approach best simulates the stressors and challenges that can be expected during clinical face transplantation. Therapeutic, V.

Three-dimensional imaging of intracochlear tissue by scanning laser optical tomography (SLOT)

NASA Astrophysics Data System (ADS)

Tinne, N.; Nolte, L.; Antonopoulos, G. C.; Schulze, J.; Andrade, J.; Heisterkamp, A.; Meyer, H.; Warnecke, A.; Majdani, O.; Ripken, T.

2016-02-01

The presented study focuses on the application of scanning laser optical tomography (SLOT) for non-destructive visualization of anatomical structures inside the human cochlea ex vivo. SLOT is a laser-based highly efficient microscopy technique, which allows for tomographic imaging of the internal structure of transparent large-scale specimens (up to 1 cm3). Thus, in the field of otology this technique is best convenient for an ex vivo study of the inner ear anatomy. For this purpose, the preparation before imaging comprises mechanically assisted decalcification, dehydration as well as optical clearing of the cochlea samples. Here, we demonstrate results of SLOT visualizing hard and soft tissue structures of the human cochlea with an optical resolution in the micrometer range using absorption and autofluorescence as contrast mechanisms. Furthermore, we compare our results with the method of X-ray micro tomography (micro-CT, μCT) as clinical gold standard which is based only on absorption. In general, SLOT can provide the advantage of covering all contrast mechanisms known from other light microscopy techniques, such as fluorescence or scattering. For this reason, a protocol for antibody staining has been developed, which additionally enables selective mapping of cellular structures within the cochlea. Thus, we present results of SLOT imaging rodent cochleae showing specific anatomical structures such as hair cells and neurofilament via fluorescence. In conclusion, the presented study has shown that SLOT is an ideally suited tool in the field of otology for in toto visualization of the inner ear microstructure.

VARIABILITY OF THE ACCRETION DISK OF V926 Sco INFERRED FROM TOMOGRAPHIC ANALYSIS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Connolly, S. D.; Peris, C. S.; Vrtilek, S. D., E-mail: sdc1g08@soton.ac.u, E-mail: peris.c@husky.neu.edu, E-mail: cperis@cfa.harvard.edu, E-mail: svrtilek@cfa.harvard.edu

2013-11-10

We present phase-resolved spectroscopic observations of the low-mass X-ray binary V926 Sco (4U 1735-44), covering the orbital period of 0.23 days, obtained with the Walter Baade 6.5 m Magellan Telescope at the Las Campanas Observatory in 2010 June and 2011 June. We use Hα radial velocities to derive a systemic velocity of –109 ± 4 km s{sup –1}. The FWHM of the lines observed in common with previous authors are significantly lower during our observations suggesting much reduced velocities in the system. The equivalent width of the Bowen fluorescence lines with respect to He II λ4686 are factors of twomore » or more lower during our observations in comparison to those previously reported for the system, suggesting reduced irradiation of the secondary. Doppler and modulation tomography of Hα and He II λ4686 show asymmetric emission that can be attributed to a bulge in the accretion disk, as inferred from He II observations by previous authors. The X-ray fluxes from the source at times concurrent with the optical observations are significantly lower during our observations than during optical observations taken in 2003. We suggest that the system is in a lower accretion state compared to earlier observations; this explains both the lower velocities observed from the disk and the reduction of emission due to Bowen fluorescence detected from the secondary.« less

TOmographic Remote Observer of Ionospheric Disturbances

DTIC Science & Technology

2007-11-15

ionosphere . The proposed spacecraft was an evolutionary design from the USUSat, Combat Sentinel, and USUSat II programs whose histories are shown in...Figure 1. The primary science instrument, TOROID for TOmographic Remote Observer of Ionospheric Disturbances, is a photometer for measuring the

Acoustic representation of tomographic data

NASA Astrophysics Data System (ADS)

Wampler, Cheryl; Zahrt, John D.; Hotchkiss, Robert S.; Zahrt, Rebecca; Kust, Mark

1993-04-01

Tomographic data and tomographic reconstructions are naturally periodic in the angle of rotation of the turntable and the polar angel of the coordinates in the object, respectively. Similarly, acoustic waves are periodic and have amplitude and wavelength as free parameters that can be fit to another representation. Work has been in progress for some time in bringing the acoustic senses to bear on large data sets rather than just the visual sense. We will provide several different acoustic representations of both raw data and density maps. Rather than graphical portrayal of the data and reconstructions, you will be presented various 'tone poems.'

Lamb wave tomographic imaging system for aircraft structural health assessment

NASA Astrophysics Data System (ADS)

Schwarz, Willi G.; Read, Michael E.; Kremer, Matthew J.; Hinders, Mark K.; Smith, Barry T.

1999-01-01

A tomographic imaging system using ultrasonic Lamb waves for the nondestructive inspection of aircraft components such as wings and fuselage is being developed. The computer-based system provides large-area inspection capability by electronically scanning an array of transducers that can be easily attached to flat and curved surface without moving parts. Images of the inspected area are produced in near real time employing a tomographic reconstruction method adapted from seismological applications. Changes in material properties caused by structural flaws such as disbonds, corrosion, and fatigue cracks can be effectively detected and characterized utilizing this fast NDE technique.

Sodankylä ionospheric tomography dataset 2003-2014

NASA Astrophysics Data System (ADS)

Norberg, J.; Roininen, L.; Kero, A.; Raita, T.; Ulich, T.; Markkanen, M.; Juusola, L.; Kauristie, K.

2015-12-01

Sodankylä Geophysical Observatory has been operating a tomographic receiver network and collecting the produced data since 2003. The collected dataset consists of phase difference curves measured from Russian COSMOS dual-frequency (150/400 MHz) low-Earth-orbit satellite signals, and tomographic electron density reconstructions obtained from these measurements. In this study vertical total electron content (VTEC) values are integrated from the reconstructed electron densities to make a qualitative and quantitative analysis to validate the long-term performance of the tomographic system. During the observation period, 2003-2014, there were three-to-five operational stations at the Fenno-Scandinavian sector. Altogether the analysis consists of around 66 000 overflights, but to ensure the quality of the reconstructions, the examination is limited to cases with descending (north to south) overflights and maximum elevation over 60°. These constraints limit the number of overflights to around 10 000. Based on this dataset, one solar cycle of ionospheric vertical total electron content estimates is constructed. The measurements are compared against International Reference Ionosphere IRI-2012 model, F10.7 solar flux index and sunspot number data. Qualitatively the tomographic VTEC estimate corresponds to reference data very well, but the IRI-2012 model are on average 40 % higher of that of the tomographic results.

Bifunctional Diaminoterephthalate Fluorescent Dye as Probe for Cross-Linking Proteins.

PubMed

Wallisch, Melanie; Sulmann, Stefan; Koch, Karl-Wilhelm; Christoffers, Jens

2017-05-11

Diaminoterephthalates are fluorescent dyes and define scaffolds, which can be orthogonally functionalized at their two carboxylate residues with functional residues bearing task specific reactive groups. The synthesis of monofunctionalized dyes with thiol groups for surface binding, an azide for click chemistry, and a biotinoylated congener for streptavidin binding is reported. Two bifunctionalized dyes were prepared: One with an azide for click chemistry and a biotin for streptavidin binding, the other with a maleimide for reaction with thiol and a cyclooctyne moiety for ligation with copper-free click chemistry. In general, the compounds are red to orange, fluorescent materials with an absorption at about 450 nm and an emission at 560 nm with quantum yields between 2-41 %. Of particular interest is the maleimide-functionalized compound, which shows low fluorescence quantum yield (2 %) by itself. After addition of a thiol, the fluorescence is "turned on"; quantum yield 41 %. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comparison of fluorescence-based methods to determine nanoparticle uptake by phagocytes and non-phagocytic cells in vitro.

PubMed

Claudia, Meindl; Kristin, Öhlinger; Jennifer, Ober; Eva, Roblegg; Eleonore, Fröhlich

2017-03-01

At many portals of entry the relative uptake by phagocytes and non-phagocytic cells has a prominent effect on availability and biological action of nanoparticles (NPs). Cellular uptake can be determined for fluorescence-labeled NPs. The present study compares three methods (plate reader, flow cytometry and image analysis) in order to investigate the influence of particle size and functionalization and medium content on cellular uptake of fluorescence-labeled polystyrene particles and to study the respective method́s suitability for uptake studies. For comparison between the techniques, ratios of macrophage to alveolar epithelial cell uptakes were used. Presence of serum protein in the exposure solution decreased uptake of carboxyl-functionalized and non-functionalized particles; there was no clear effect for the amine-functionalized particles. The 200nm non- or carboxyl-functionalized NPs were taken up preferentially by phagocytes while for amine-functionalized particles preference was lowest. The presence of the serum slightly increased the preference for these particles. In conclusion, due to the possibility of calibration, plate reader measurements might present a better option than the other techniques to (semi)quantify differences between phagocytes and non-phagocytic cells for particles with different fluorescence. In order to obtain unbiased data the fluorescent labeling has to fulfill certain requirements. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

Efficient volumetric estimation from plenoptic data

NASA Astrophysics Data System (ADS)

Anglin, Paul; Reeves, Stanley J.; Thurow, Brian S.

2013-03-01

The commercial release of the Lytro camera, and greater availability of plenoptic imaging systems in general, have given the image processing community cost-effective tools for light-field imaging. While this data is most commonly used to generate planar images at arbitrary focal depths, reconstruction of volumetric fields is also possible. Similarly, deconvolution is a technique that is conventionally used in planar image reconstruction, or deblurring, algorithms. However, when leveraged with the ability of a light-field camera to quickly reproduce multiple focal planes within an imaged volume, deconvolution offers a computationally efficient method of volumetric reconstruction. Related research has shown than light-field imaging systems in conjunction with tomographic reconstruction techniques are also capable of estimating the imaged volume and have been successfully applied to particle image velocimetry (PIV). However, while tomographic volumetric estimation through algorithms such as multiplicative algebraic reconstruction techniques (MART) have proven to be highly accurate, they are computationally intensive. In this paper, the reconstruction problem is shown to be solvable by deconvolution. Deconvolution offers significant improvement in computational efficiency through the use of fast Fourier transforms (FFTs) when compared to other tomographic methods. This work describes a deconvolution algorithm designed to reconstruct a 3-D particle field from simulated plenoptic data. A 3-D extension of existing 2-D FFT-based refocusing techniques is presented to further improve efficiency when computing object focal stacks and system point spread functions (PSF). Reconstruction artifacts are identified; their underlying source and methods of mitigation are explored where possible, and reconstructions of simulated particle fields are provided.

Stereo-tomography in triangulated models

NASA Astrophysics Data System (ADS)

Yang, Kai; Shao, Wei-Dong; Xing, Feng-yuan; Xiong, Kai

2018-04-01

Stereo-tomography is a distinctive tomographic method. It is capable of estimating the scatterer position, the local dip of scatterer and the background velocity simultaneously. Building a geologically consistent velocity model is always appealing for applied and earthquake seismologists. Differing from the previous work to incorporate various regularization techniques into the cost function of stereo-tomography, we think extending stereo-tomography to the triangulated model will be the most straightforward way to achieve this goal. In this paper, we provided all the Fréchet derivatives of stereo-tomographic data components with respect to model components for slowness-squared triangulated model (or sloth model) in 2D Cartesian coordinate based on the ray perturbation theory for interfaces. A sloth model representation means a sparser model representation when compared with conventional B-spline model representation. A sparser model representation leads to a smaller scale of stereo-tomographic (Fréchet) matrix, a higher-accuracy solution when solving linear equations, a faster convergence rate and a lower requirement for quantity of data space. Moreover, a quantitative representation of interface strengthens the relationships among different model components, which makes the cross regularizations among these model components, such as node coordinates, scatterer coordinates and scattering angles, etc., more straightforward and easier to be implemented. The sensitivity analysis, the model resolution matrix analysis and a series of synthetic data examples demonstrate the correctness of the Fréchet derivatives, the applicability of the regularization terms and the robustness of the stereo-tomography in triangulated model. It provides a solid theoretical foundation for the real applications in the future.

Anisotropic full waveform ambient noise and earthquake tomography of the Ontong Java Plateau and surrounding Pacific upper mantle

NASA Astrophysics Data System (ADS)

Hirsch, A. C.; Savage, B.; Shen, Y.

2017-12-01

The Ontong Java (OJP) and Manihiki plateau (MP) large igneous provinces (LIP) of the Southwest Pacific took shape from a complicated, but poorly understood geological history. Unraveling the formation and deformation of these Pacific LIPs is not straightforward due to limited available data, remote location, and atypical geology. Origin hypotheses include melting of a plume or a fast-spreading triple junction, but distinguishing between these requires a further understanding of 120 Ma of deformation of each LIP. A previous tomographic model of OJP observed highly abnormal Rayleigh shear wave speeds, >4.75km/s, and attributed these to an unusual composition, garnet and clinopyroxene residual from melting pyroxenite entrained within a rising plume. Unfortunately, this model lacks constraints on the horizontally polarized shear wave speeds, SH or Love waves, anisotropy, and attenuation. We therefore perform a transverse-isotropic, scattering-integral, full-waveform tomography between periods of 25 and 200 seconds utilizing both ambient noise empirical Green's functions and seismic data from regional earthquakes. Our tomographic model improves upon previous work using permanent and temporary seismic stations, increased model space, and utilizing three components of seismic data (vertical, radial, and tangential). Included is also an assessment of the anelastic attenuation in the western Pacific using both surface waves and multiple core reflections. Our results will improve the tomographic resolution around OJP and the Pacific upper mantle between 35 and 300 km depth. This improved model will enhance our understanding of the tectonic history of the OJP and MP regions, and the Pacific Indo-Australian plate boundary.

Angular ellipticity correlations in a composite alignment model for elliptical and spiral galaxies and inference from weak lensing

NASA Astrophysics Data System (ADS)

Tugendhat, Tim M.; Schäfer, Björn Malte

2018-05-01

We investigate a physical, composite alignment model for both spiral and elliptical galaxies and its impact on cosmological parameter estimation from weak lensing for a tomographic survey. Ellipticity correlation functions and angular ellipticity spectra for spiral and elliptical galaxies are derived on the basis of tidal interactions with the cosmic large-scale structure and compared to the tomographic weak-lensing signal. We find that elliptical galaxies cause a contribution to the weak-lensing dominated ellipticity correlation on intermediate angular scales between ℓ ≃ 40 and ℓ ≃ 400 before that of spiral galaxies dominates on higher multipoles. The predominant term on intermediate scales is the negative cross-correlation between intrinsic alignments and weak gravitational lensing (GI-alignment). We simulate parameter inference from weak gravitational lensing with intrinsic alignments unaccounted; the bias induced by ignoring intrinsic alignments in a survey like Euclid is shown to be several times larger than the statistical error and can lead to faulty conclusions when comparing to other observations. The biases generally point into different directions in parameter space, such that in some cases one can observe a partial cancellation effect. Furthermore, it is shown that the biases increase with the number of tomographic bins used for the parameter estimation process. We quantify this parameter estimation bias in units of the statistical error and compute the loss of Bayesian evidence for a model due to the presence of systematic errors as well as the Kullback-Leibler divergence to quantify the distance between the true model and the wrongly inferred one.

Tomographic reconstruction of atmospheric gravity wave parameters from airglow observations

NASA Astrophysics Data System (ADS)

Song, Rui; Kaufmann, Martin; Ungermann, Jörn; Ern, Manfred; Liu, Guang; Riese, Martin

2017-11-01

Gravity waves (GWs) play an important role in the dynamics of the mesosphere and lower thermosphere (MLT). Therefore, global observations of GWs in the MLT region are of particular interest. The small scales of GWs, however, pose a major problem for the observation of GWs from space. We propose a new observation strategy for GWs in the mesopause region by combining limb and sub-limb satellite-borne remote sensing measurements for improving the spatial resolution of temperatures that are retrieved from atmospheric soundings. In our study, we simulate satellite observations of the rotational structure of the O2 A-band nightglow. A key element of the new method is the ability of the instrument or the satellite to operate in so-called target mode, i.e. to point at a particular point in the atmosphere and collect radiances at different viewing angles. These multi-angle measurements of a selected region allow for tomographic 2-D reconstruction of the atmospheric state, in particular of GW structures. The feasibility of this tomographic retrieval approach is assessed using simulated measurements. It shows that one major advantage of this observation strategy is that GWs can be observed on a much smaller scale than conventional observations. We derive a GW sensitivity function, and it is shown that target mode observations are able to capture GWs with horizontal wavelengths as short as ˜ 50 km for a large range of vertical wavelengths. This is far better than the horizontal wavelength limit of 100-200 km obtained from conventional limb sounding.

[Assessment of mitochondrial metabolic oxidative state in living cardiomyocytes with spectrally-resolved fluorescence lifetime spectroscopy of NAD(P)H].

PubMed

Cheng, Ying; Ren, Mingming; Niu, Yanyan; Qiao, Jianhua; Aneba, S; Chorvat, D; Chorvatova, A

2009-12-01

The primary function of cardiac mitochondria is the production of ATP to support heart contraction. Examination of the mitochondrial redox state is therefore crucially important to sensitively detect early signs of mitochondrial function in pathophysiological conditions, such as ischemia, diabetes and heart failure. We study fingerprinting of mitochondrial metabolic oxidative state in living cardiomyocytes with spectrally-resolved fluorescence lifetime spectroscopy of NAD(P)H, the principal electron donor in mitochondrial respiration responsible for vital ATP supply. Here NAD(P)H is studied as a marker for non-invasive fluorescent probing of the mitochondrial function. NAD(P) H fluorescence is recorded in cardiac cells following excitation with 375nm UV-light and detection by spectrally-resolved time-correlated single photon counting (TCSPC), based on the simultaneous measurement of the fluorescence spectra and fluorescence lifetimes. Modulation of NADH production and/or mitochondrial respiration is tested to study dynamic characteristics of NAD(P) H fluorescence decay. Our results show that at least a 3-exponential decay model, with 0.4-0.7ns, 1.2-1.9ns and 8.0-13. Ons lifetime pools is necessary to describe cardiomyocyte autofluorescence (AF) within 420-560nm spectral range. Increased mitochondrial NADH production by ketone bodies enhanced the fluorescence intensity, without significant change in fluorescent lifetimes. Rotenone, the inhibitor of Complex I of the mitochondrial respiratory chain, increased AF intensity and shortened the average fluorescence lifetime. Dinitrophenol (DNP), an uncoupling agent of the mitochondrial oxidative phosphorylation, lowered AF intensity, broadened the spectral shoulder at 520 nm and increased the average fluorescence lifetime. These effects are comparable to the study of NADH fluorescence decay in vitro. In the present contribution we demonstrated that spectrally-resolved fluorescence lifetime technique provides promising new tool for analysis of mitochondrial NAD(P) H fluorescence with good reproducibility in living cardiomyocytes. This approach will enhance our knowledge about cardiomyocyte oxidative metabolism and/or its dysfunction at a cellular level. In the future, this approach can prove helpful in the clinical diagnosis and treatment of mitochondrial disorder.

Tomographic Image Compression Using Multidimensional Transforms.

ERIC Educational Resources Information Center

Villasenor, John D.

1994-01-01

Describes a method for compressing tomographic images obtained using Positron Emission Tomography (PET) and Magnetic Resonance (MR) by applying transform compression using all available dimensions. This takes maximum advantage of redundancy of the data, allowing significant increases in compression efficiency and performance. (13 references) (KRN)

Finite-frequency tomography using adjoint methods-Methodology and examples using membrane surface waves

NASA Astrophysics Data System (ADS)

Tape, Carl; Liu, Qinya; Tromp, Jeroen

2007-03-01

We employ adjoint methods in a series of synthetic seismic tomography experiments to recover surface wave phase-speed models of southern California. Our approach involves computing the Fréchet derivative for tomographic inversions via the interaction between a forward wavefield, propagating from the source to the receivers, and an `adjoint' wavefield, propagating from the receivers back to the source. The forward wavefield is computed using a 2-D spectral-element method (SEM) and a phase-speed model for southern California. A `target' phase-speed model is used to generate the `data' at the receivers. We specify an objective or misfit function that defines a measure of misfit between data and synthetics. For a given receiver, the remaining differences between data and synthetics are time-reversed and used as the source of the adjoint wavefield. For each earthquake, the interaction between the regular and adjoint wavefields is used to construct finite-frequency sensitivity kernels, which we call event kernels. An event kernel may be thought of as a weighted sum of phase-specific (e.g. P) banana-doughnut kernels, with weights determined by the measurements. The overall sensitivity is simply the sum of event kernels, which defines the misfit kernel. The misfit kernel is multiplied by convenient orthonormal basis functions that are embedded in the SEM code, resulting in the gradient of the misfit function, that is, the Fréchet derivative. A non-linear conjugate gradient algorithm is used to iteratively improve the model while reducing the misfit function. We illustrate the construction of the gradient and the minimization algorithm, and consider various tomographic experiments, including source inversions, structural inversions and joint source-structure inversions. Finally, we draw connections between classical Hessian-based tomography and gradient-based adjoint tomography.

Functional assessment of gap junctions in monolayer and three-dimensional cultures of human tendon cells using fluorescence recovery after photobleaching

PubMed Central

Kuzma-Kuzniarska, Maria; Yapp, Clarence; Pearson-Jones, Thomas W.; Jones, Andrew K.; Hulley, Philippa A.

2014-01-01

Abstract. Gap junction-mediated intercellular communication influences a variety of cellular activities. In tendons, gap junctions modulate collagen production, are involved in strain-induced cell death, and are involved in the response to mechanical stimulation. The aim of the present study was to investigate gap junction-mediated intercellular communication in healthy human tendon-derived cells using fluorescence recovery after photobleaching (FRAP). The FRAP is a noninvasive technique that allows quantitative measurement of gap junction function in living cells. It is based on diffusion-dependent redistribution of a gap junction-permeable fluorescent dye. Using FRAP, we showed that human tenocytes form functional gap junctions in monolayer and three-dimensional (3-D) collagen I culture. Fluorescently labeled tenocytes following photobleaching rapidly reacquired the fluorescent dye from neighboring cells, while HeLa cells, which do not communicate by gap junctions, remained bleached. Furthermore, both 18 β-glycyrrhetinic acid and carbenoxolone, standard inhibitors of gap junction activity, impaired fluorescence recovery in tendon cells. In both monolayer and 3-D cultures, intercellular communication in isolated cells was significantly decreased when compared with cells forming many cell-to-cell contacts. In this study, we used FRAP as a tool to quantify and experimentally manipulate the function of gap junctions in human tenocytes in both two-dimensional (2-D) and 3-D cultures. PMID:24390370

High fluorescence emission of carboxylic acid functionalized polystyrene/BaTiO{sub 3} nanocomposites and rare earth metal complexes: Preparation and characterization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cao, X. T.; Showkat, A. M.; Wang, Z.

2015-03-30

Noble fluorescence nanocomposite compound based on barium titanate nanoparticles (BTO), polystyrene (PSt), and terbium ion (Tb{sup 3+}) was synthesized by a combination of surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization, Friedel-Crafts alkylation reaction and coordinate chemistry. Initially, a modification of surface of BTO was conducted by an exchange process with S-benzyl S’-trimethoxysilylpropyltrithiocarbonate to create macro-initiator for polymerization of styrene. Subsequently, aryl carboxylic acid functionalized polystyrene grafted barium titanate (BTO-g-PSt-COOH) was generated by substitution reaction between 4-(Chloromethyl) benzoic acid and PSt chains. The coordination of the nanohybrids with Tb{sup 3+} ions afforded fluorescent Tb{sup 3+} tagged aryl carboxylic acid functionalized polystyrenemore » grafted barium titanate (BTO-g-PSt-Tb{sup 3+}) complexes. Structure, morphology, and fluorescence properties of nanohybrid complexes were investigated by respective physical and spectral studies. FT-IR and SEM analyses confirmed the formation of BTO-g-PSt-Tb{sup 3+}nanohybrids. Furthermore, TGA profiles demonstrated the grafting of aryl carboxylic acid functionalized polystyrene on BTO surface. Optical properties of BTO-g-PSt-Tb{sup 3+} complexes were investigated by fluorescence spectroscopy.« less

Images of photoreceptors in living primate eyes using adaptive optics two-photon ophthalmoscopy

PubMed Central

Hunter, Jennifer J.; Masella, Benjamin; Dubra, Alfredo; Sharma, Robin; Yin, Lu; Merigan, William H.; Palczewska, Grazyna; Palczewski, Krzysztof; Williams, David R.

2011-01-01

In vivo two-photon imaging through the pupil of the primate eye has the potential to become a useful tool for functional imaging of the retina. Two-photon excited fluorescence images of the macaque cone mosaic were obtained using a fluorescence adaptive optics scanning laser ophthalmoscope, overcoming the challenges of a low numerical aperture, imperfect optics of the eye, high required light levels, and eye motion. Although the specific fluorophores are as yet unknown, strong in vivo intrinsic fluorescence allowed images of the cone mosaic. Imaging intact ex vivo retina revealed that the strongest two-photon excited fluorescence signal comes from the cone inner segments. The fluorescence response increased following light stimulation, which could provide a functional measure of the effects of light on photoreceptors. PMID:21326644

Enhanced Fluorescence Properties of Carbon Dots in Polymer Films

PubMed Central

Liu, Yamin; Wang, Ping; Shiral Fernando, K. A.; LeCroy, Gregory E.; Maimaiti, Halidan; Harruff-Miller, Barbara A.; Lewis, William K.; Bunker, Christopher E.; Hou, Zhi-Ling; Sun, Ya-Ping

2016-01-01

Carbon dots of small carbon nanoparticles surface-functionalized with 2,2′-(ethylenedioxy)bis(ethylamine) (EDA) were synthesized, and the as-synthesized sample was separated on an aqueous gel column to obtain fractions of the EDA-carbon dots with different fluorescence quantum yields. As already discussed in the literature, the variations in fluorescence performance among the fractions were attributed to the different levels and/or effectiveness of the surface functionalization-passivation in the carbon dots. These fractions, as well as carbon nanoparticles without any deliberate surface functionalization, were dispersed into poly(vinyl alcohol) (PVA) for composite films. In the PVA film matrix, the carbon dots and nanoparticles exhibited much enhanced fluorescence emissions in comparison with their corresponding aqueous solutions. The increased fluorescence quantum yields in the films were determined quantitatively by using a specifically designed and constructed film sample holder in the emission spectrometer. The observed fluorescence decays of the EDA-carbon dots in film and in solution were essentially the same, suggesting that the significant enhancement in fluorescence quantum yields from solution to film is static in nature. Mechanistic implications of the results, including a rationalization in terms of the compression effect on the surface passivation layer (similar to a soft corona) in carbon dots when embedded in the more restrictive film environment resulting in more favorable radiative recombinations of the carbon particle surface-trapped electrons and holes, and also potential technological applications of the brightly fluorescent composite films are highlighted and discussed. PMID:28133537

Investigation of OPET Performance Using GATE, a Geant4-Based Simulation Software.

PubMed

Rannou, Fernando R; Kohli, Vandana; Prout, David L; Chatziioannou, Arion F

2004-10-01

A combined optical positron emission tomography (OPET) system is capable of both optical and PET imaging in the same setting, and it can provide information/interpretation not possible in single-mode imaging. The scintillator array here serves the dual function of coupling the optical signal from bioluminescence/fluorescence to the photodetector and also of channeling optical scintillations from the gamma rays. We report simulation results of the PET part of OPET using GATE, a Geant4 simulation package. The purpose of this investigation is the definition of the geometric parameters of the OPET tomograph. OPET is composed of six detector blocks arranged in a hexagonal ring-shaped pattern with an inner radius of 15.6 mm. Each detector consists of a two-dimensional array of 8 × 8 scintillator crystals each measuring 2 × 2 × 10 mm(3). Monte Carlo simulations were performed using the GATE software to measure absolute sensitivity, depth of interaction, and spatial resolution for two ring configurations, with and without gantry rotations, two crystal materials, and several crystal lengths. Images were reconstructed with filtered backprojection after angular interleaving and transverse one-dimensional interpolation of the sinogram. We report absolute sensitivities nearly seven times that of the prototype microPET at the center of field of view and 2.0 mm tangential and 2.3 mm radial resolutions with gantry rotations up to an 8.0 mm radial offset. These performance parameters indicate that the imaging spatial resolution and sensitivity of the OPET system will be suitable for high-resolution and high-sensitivity small-animal PET imaging.

Multimodal Light Microscopy Approaches to Reveal Structural and Functional Properties of Promyelocytic Leukemia Nuclear Bodies

PubMed Central

Hoischen, Christian; Monajembashi, Shamci; Weisshart, Klaus; Hemmerich, Peter

2018-01-01

The promyelocytic leukemia (pml) gene product PML is a tumor suppressor localized mainly in the nucleus of mammalian cells. In the cell nucleus, PML seeds the formation of macromolecular multiprotein complexes, known as PML nuclear bodies (PML NBs). While PML NBs have been implicated in many cellular functions including cell cycle regulation, survival and apoptosis their role as signaling hubs along major genome maintenance pathways emerged more clearly. However, despite extensive research over the past decades, the precise biochemical function of PML in these pathways is still elusive. It remains a big challenge to unify all the different previously suggested cellular functions of PML NBs into one mechanistic model. With the advent of genetically encoded fluorescent proteins it became possible to trace protein function in living specimens. In parallel, a variety of fluorescence fluctuation microscopy (FFM) approaches have been developed which allow precise determination of the biophysical and interaction properties of cellular factors at the single molecule level in living cells. In this report, we summarize the current knowledge on PML nuclear bodies and describe several fluorescence imaging, manipulation, FFM, and super-resolution techniques suitable to analyze PML body assembly and function. These include fluorescence redistribution after photobleaching, fluorescence resonance energy transfer, fluorescence correlation spectroscopy, raster image correlation spectroscopy, ultraviolet laser microbeam-induced DNA damage, erythrocyte-mediated force application, and super-resolution microscopy approaches. Since most if not all of the microscopic equipment to perform these techniques may be available in an institutional or nearby facility, we hope to encourage more researches to exploit sophisticated imaging tools for their research in cancer biology. PMID:29888200

The Mathematics of Four or More N-Localizers for Stereotactic Neurosurgery.

PubMed

Brown, Russell A

2015-10-13

The mathematics that were originally developed for the N-localizer apply to three N-localizers that produce three sets of fiducials in a tomographic image. Some applications of the N-localizer use four N-localizers that produce four sets of fiducials; however, the mathematics that apply to three sets of fiducials do not apply to four sets of fiducials. This article presents mathematics that apply to four or more sets of fiducials that all lie within one planar tomographic image. In addition, these mathematics are extended to apply to four or more fiducials that do not all lie within one planar tomographic image, as may be the case with magnetic resonance (MR) imaging where a volume is imaged instead of a series of planar tomographic images. Whether applied to a planar image or a volume image, the mathematics of four or more N-localizers provide a statistical measure of the quality of the image data that may be influenced by factors, such as the nonlinear distortion of MR images.

TomoBank: a tomographic data repository for computational x-ray science

DOE PAGES

De Carlo, Francesco; Gürsoy, Doğa; Ching, Daniel J.; ...

2018-02-08

There is a widening gap between the fast advancement of computational methods for tomographic reconstruction and their successful implementation in production software at various synchrotron facilities. This is due in part to the lack of readily available instrument datasets and phantoms representative of real materials for validation and comparison of new numerical methods. Recent advancements in detector technology made sub-second and multi-energy tomographic data collection possible [1], but also increased the demand to develop new reconstruction methods able to handle in-situ [2] and dynamic systems [3] that can be quickly incorporated in beamline production software [4]. The X-ray Tomography Datamore » Bank, tomoBank, provides a repository of experimental and simulated datasets with the aim to foster collaboration among computational scientists, beamline scientists, and experimentalists and to accelerate the development and implementation of tomographic reconstruction methods for synchrotron facility production software by providing easy access to challenging dataset and their descriptors.« less

Nuclear medicine in clinical neurology: an update

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oldendorf, W.H.

1981-01-01

Isotope scanning using technetium 99m pertechnetate has fallen into disuse since the advent of x-ray computerized tomography. Regional brain blood flow studies have been pursued on a research basis. Increased regional blood flow during focal seizure activity has been demonstrated and is of use in localizing such foci. Cisternography as a predictive tool in normal pressure hydrocephalus is falling into disuse. Positron tomographic scanning is a potent research tool that can demonstrate both regional glycolysis and blood flow. Unfortunately, it is extremely expensive and complex to apply in a clinical setting. With support from the National Institutes of Health, sevenmore » extramural centers have been funded to develop positron tomographic capabilities, and they will greatly advance our knowledge of stroke pathophysiology, seizure disorders, brain tumors, and various degenerative diseases. Nuclear magnetic resonance imaging is a potentially valuable tool since it creates tomographic images representing the distribution of brain water. No tissue ionization is produced, and images comparable to second-generation computerized tomographic scans are already being produced in humans.« less

Tomographic findings of acute pulmonary toxoplasmosis in immunocompetent patients.

PubMed

de Souza Giassi, Karina; Costa, Andre Nathan; Apanavicius, Andre; Teixeira, Fernando Bin; Fernandes, Caio Julio Cesar; Helito, Alfredo Salim; Kairalla, Ronaldo Adib

2014-11-25

Toxoplasmosis is one of the most common human zoonosis, and is generally benign in most of the individuals. Pulmonary involvement is common in immunocompromised subjects, but very rare in immunocompetents and there are scarce reports of tomographic findings in the literature. The aim of the study is to describe three immunocompetent patients diagnosed with acute pulmonary toxoplasmosis and their respective thoracic tomographic findings. Acute toxoplasmosis was diagnosed according to the results of serological tests suggestive of recent primary infection and the absence of an alternative etiology. From 2009 to 2013, three patients were diagnosed with acute respiratory failure secondary to acute toxoplasmosis. The patients were two female and one male, and were 38, 56 and 36 years old. Similarly they presented a two-week febrile illness and progressive dyspnea before admission. Laboratory tests demonstrated lymphocytosis, slight changes in liver enzymes and high inflammatory markers. Tomographic findings were bilateral smooth septal and peribronchovascular thickening (100%), ground-glass opacities (100%), atelectasis (33%), random nodules (33%), lymph node enlargement (33%) and pleural effusion (66%). All the patients improved their symptoms after treatment, and complete resolution of tomographic findings were found in the followup. These cases provide a unique description of the presentation and evolution of pulmonary tomographic manifestations of toxoplasmosis in immunocompetent patients. Toxoplasma pneumonia manifests with fever, dyspnea and a non-productive cough that may result in respiratory failure. In animal models, changes were described as interstitial pneumonitis with focal infiltrates of neutrophils that can finally evolve into a pattern of diffuse alveolar damage with focal necrosis. The tomographic findings are characterized as ground glass opacities, smooth septal and marked peribronchovascular thickening; and may mimic pulmonary congestion, lymphangitis, atypical pneumonia and pneumocystosis. This is the largest series of CT findings of acute toxoplasmosis in immunocompetent hosts, and the diagnosis should be considered as patients that present with acute respiratory failure in the context of a subacute febrile illness with bilateral and diffuse interstitial infiltrates with marked peribronchovascular thickening. If promptly treated, pulmonary toxoplasmosis can result in complete clinical and radiological recovery in immunocompetent hosts.

Controlled wavelet domain sparsity for x-ray tomography

NASA Astrophysics Data System (ADS)

Purisha, Zenith; Rimpeläinen, Juho; Bubba, Tatiana; Siltanen, Samuli

2018-01-01

Tomographic reconstruction is an ill-posed inverse problem that calls for regularization. One possibility is to require sparsity of the unknown in an orthonormal wavelet basis. This, in turn, can be achieved by variational regularization, where the penalty term is the sum of the absolute values of the wavelet coefficients. The primal-dual fixed point algorithm showed that the minimizer of the variational regularization functional can be computed iteratively using a soft-thresholding operation. Choosing the soft-thresholding parameter \

A Kullback-Leibler approach for 3D reconstruction of spectral CT data corrupted by Poisson noise

NASA Astrophysics Data System (ADS)

Hohweiller, Tom; Ducros, Nicolas; Peyrin, Françoise; Sixou, Bruno

2017-09-01

While standard computed tomography (CT) data do not depend on energy, spectral computed tomography (SPCT) acquire energy-resolved data, which allows material decomposition of the object of interest. Decompo- sitions in the projection domain allow creating projection mass density (PMD) per materials. From decomposed projections, a tomographic reconstruction creates 3D material density volume. The decomposition is made pos- sible by minimizing a cost function. The variational approach is preferred since this is an ill-posed non-linear inverse problem. Moreover, noise plays a critical role when decomposing data. That is why in this paper, a new data fidelity term is used to take into account of the photonic noise. In this work two data fidelity terms were investigated: a weighted least squares (WLS) term, adapted to Gaussian noise, and the Kullback-Leibler distance (KL), adapted to Poisson noise. A regularized Gauss-Newton algorithm minimizes the cost function iteratively. Both methods decompose materials from a numerical phantom of a mouse. Soft tissues and bones are decomposed in the projection domain; then a tomographic reconstruction creates a 3D material density volume for each material. Comparing relative errors, KL is shown to outperform WLS for low photon counts, in 2D and 3D. This new method could be of particular interest when low-dose acquisitions are performed.

Tomographic PIV: particles versus blobs

NASA Astrophysics Data System (ADS)

Champagnat, Frédéric; Cornic, Philippe; Cheminet, Adam; Leclaire, Benjamin; Le Besnerais, Guy; Plyer, Aurélien

2014-08-01

We present an alternative approach to tomographic particle image velocimetry (tomo-PIV) that seeks to recover nearly single voxel particles rather than blobs of extended size. The baseline of our approach is a particle-based representation of image data. An appropriate discretization of this representation yields an original linear forward model with a weight matrix built with specific samples of the system’s point spread function (PSF). Such an approach requires only a few voxels to explain the image appearance, therefore it favors much more sparsely reconstructed volumes than classic tomo-PIV. The proposed forward model is general and flexible and can be embedded in a classical multiplicative algebraic reconstruction technique (MART) or a simultaneous multiplicative algebraic reconstruction technique (SMART) inversion procedure. We show, using synthetic PIV images and by way of a large exploration of the generating conditions and a variety of performance metrics, that the model leads to better results than the classical tomo-PIV approach, in particular in the case of seeding densities greater than 0.06 particles per pixel and of PSFs characterized by a standard deviation larger than 0.8 pixels.

Diffuse Optical Tomography for Brain Imaging: Continuous Wave Instrumentation and Linear Analysis Methods

NASA Astrophysics Data System (ADS)

Giacometti, Paolo; Diamond, Solomon G.

Diffuse optical tomography (DOT) is a functional brain imaging technique that measures cerebral blood oxygenation and blood volume changes. This technique is particularly useful in human neuroimaging measurements because of the coupling between neural and hemodynamic activity in the brain. DOT is a multichannel imaging extension of near-infrared spectroscopy (NIRS). NIRS uses laser sources and light detectors on the scalp to obtain noninvasive hemodynamic measurements from spectroscopic analysis of the remitted light. This review explains how NIRS data analysis is performed using a combination of the modified Beer-Lambert law (MBLL) and the diffusion approximation to the radiative transport equation (RTE). Laser diodes, photodiode detectors, and optical terminals that contact the scalp are the main components in most NIRS systems. Placing multiple sources and detectors over the surface of the scalp allows for tomographic reconstructions that extend the individual measurements of NIRS into DOT. Mathematically arranging the DOT measurements into a linear system of equations that can be inverted provides a way to obtain tomographic reconstructions of hemodynamics in the brain.

Morphometric analysis of erythrocytes from patients with thalassemia using tomographic diffractive microscopy

NASA Astrophysics Data System (ADS)

Lin, Yang-Hsien; Huang, Shin-Shyang; Wu, Shang-Ju; Sung, Kung-Bin

2017-11-01

Complete blood count is the most common test to detect anemia, but it is unable to obtain the abnormal shape of erythrocytes, which highly correlates with the hematologic function. Tomographic diffractive microscopy (TDM) is an emerging technique capable of quantifying three-dimensional (3-D) refractive index (RI) distributions of erythrocytes without labeling. TDM was used to characterize optical and morphological properties of 172 erythrocytes from healthy volunteers and 419 erythrocytes from thalassemic patients. To efficiently extract and analyze the properties of erythrocytes, we developed an adaptive region-growing method for automatically delineating erythrocytes from 3-D RI maps. The thalassemic erythrocytes not only contained lower hemoglobin content but also showed doughnut shape and significantly lower volume, surface area, effective radius, and average thickness. A multi-indices prediction model achieved perfect accuracy of diagnosing thalassemia using four features, including the optical volume, surface-area-to-volume ratio, sphericity index, and surface area. The results demonstrate the ability of TDM to provide quantitative, hematologic measurements and to assess morphological features of erythrocytes to distinguish healthy and thalassemic erythrocytes.

Tomographic PIV of flow through ordered thin porous media

NASA Astrophysics Data System (ADS)

Larsson, I. A. Sofia; Lundström, T. Staffan; Lycksam, Henrik

2018-06-01

Pressure-driven flow in a model of a thin porous medium is investigated using tomographic particle image velocimetry. The solid parts of the porous medium have the shape of vertical cylinders placed on equal interspatial distance from each other. The array of cylinders is confined between two parallel plates, meaning that the permeability is a function of the diameter and height of the cylinders, as well as their interspatial distance. Refractive index matching is applied to enable measurements without optical distortion and a dummy cell is used for the calibration of the measurements. The results reveal that the averaged flow field changes substantially as Reynolds number increases, and that the wakes formed downstream the cylinders contain complex, three-dimensional vortex structures hard to visualize with only planar measurements. An interesting observation is that the time-averaged velocity maximum changes position as Reynolds number increases. For low Reynolds number flow, the maximum is in the middle of the channel, while, for the higher Reynolds numbers investigated, two maxima appear closer to each bounding lower and upper wall.

Perforating internal root resorption repaired with mineral trioxide aggregate caused complete resolution of odontogenic sinus mucositis: a case report.

PubMed

Bendyk-Szeffer, Maja; Łagocka, Ryta; Trusewicz, Matylda; Lipski, Mariusz; Buczkowska-Radlińska, Jadwiga

2015-02-01

An extensive perforating internal root resorption accompanied by apical periodontitis and odontogenic sinus mucositis was detected on preoperative cone-beam computed tomographic scans in a first maxillary molar. After the chemomechanical debridement of the root canals, calcium hydroxide was placed as a temporary dressing for 7 days. Mineral trioxide aggregate was used to fill the perforation site with the aid of a surgical microscope. At the next visit, the root with the resorption defect was filled with warm vertical compaction of gutta-percha. A control cone-beam computed tomographic scan acquired 6 months after the endodontic treatment revealed complete resolution of the sinus retention cyst. Moreover, the patient's frequent otolaryngologic disturbances ceased. The tooth was functional with satisfactory clinical and radiographic results after 12 months. Based on the results of this case, successful repair of an extensive, perforating internal resorption with mineral trioxide aggregate may lead to complete resolution of apical periodontitis and maxillary sinus retention cyst. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Clamshell tomograph

DOEpatents

Derenzo, Stephen E.; Budinger, Thomas F.

1984-01-01

In brief, the invention is a tomograph modified to be in a clamshell configuration so that the ring or rings may be moved to multiple sampling positions. The tomograph includes an array of detectors arranged in successive adjacent relative locations along a closed curve in a first position in a selected plane, and means for securing the detectors in the relative locations in a first sampling position. The securing means is movable in the plane in two sections and pivotable at one p The U.S. Government has rights in this invention pursuant to Contract No. W-7405-ENG-48 between the U.S. Department of Energy and the University of California.

Protein-binding aptamer assisted signal amplification for the detection of influenza A (H1N1) DNA sequences based on quantum dot fluorescence polarization analysis.

PubMed

Zhang, Juanni; Tian, Jianniao; He, Yanlong; Chen, Sheng; Jiang, Yixuan; Zhao, Yanchun; Zhao, Shulin

2013-09-07

We report a fluorescence polarization platform for H1N1 detection based on the construction of a DNA functional QD fluorescence polarization probe and a bi-functional protein binding aptamer (Apt-DNA). The assay has a linear range from 10 nM to 100 nM with a detection limit of 3.45 nM and is selective over the mismatched bases.

Benzofurazan Sulfides for Thiol Imaging and Quantification in Live Cells through Fluorescence Microscopy

PubMed Central

Li, Yinghong; Yang, Yang; Guan, Xiangming

2012-01-01

Thiol groups play a significant role in various cellular functions. Cellular thiol concentrations can be affected by various physiological or pathological factors. A fluorescence imaging agent that can effectively and specifically image thiols in live cells through fluorescence microscopy is desirable for live cell thiol monitoring. Benzofurazan sulfides 1a–e were synthesized and found to be thiol specific fluorogenic agents except 1d. They are not fluorescent but form strong fluorescent thiol adducts after reacting with thiols through a sulfide-thiol exchange reaction. On the other hand, they exhibit no reaction with other biologically relevant nucleophilic functional groups such as -NH2, -OH, or -COOH revealing the specificity for the detection of thiols. Sulfide 1a was selected to confirm its ability to image cellular thiols through fluorescence microscopy. The compound was demonstrated to effectively image and quantify thiol changes in live cells through fluorescence microscopy using 430 nm and 520 nm as the excitation and emission wavelengths respectively. The quantification results of total thiol in live cells obtained from fluorescence microscopy were validated by an HPLC/UV total thiol assay method. The reagents and method will be of a great value to thiol redox-related research. PMID:22794193

A 3D imaging system integrating photoacoustic and fluorescence orthogonal projections for anatomical, functional and molecular assessment of rodent models

NASA Astrophysics Data System (ADS)

Brecht, Hans P.; Ivanov, Vassili; Dumani, Diego S.; Emelianov, Stanislav Y.; Anastasio, Mark A.; Ermilov, Sergey A.

2018-03-01

We have developed a preclinical 3D imaging instrument integrating photoacoustic tomography and fluorescence (PAFT) addressing known deficiencies in sensitivity and spatial resolution of the individual imaging components. PAFT is designed for simultaneous acquisition of photoacoustic and fluorescence orthogonal projections at each rotational position of a biological object, enabling direct registration of the two imaging modalities. Orthogonal photoacoustic projections are utilized to reconstruct large (21 cm3 ) volumes showing vascularized anatomical structures and regions of induced optical contrast with spatial resolution exceeding 100 µm. The major advantage of orthogonal fluorescence projections is significant reduction of background noise associated with transmitted or backscattered photons. The fluorescence imaging component of PAFT is used to boost detection sensitivity by providing low-resolution spatial constraint for the fluorescent biomarkers. PAFT performance characteristics were assessed by imaging optical and fluorescent contrast agents in tissue mimicking phantoms and in vivo. The proposed PAFT technology will enable functional and molecular volumetric imaging using fluorescent biomarkers, nanoparticles, and other photosensitive constructs mapped with high fidelity over robust anatomical structures, such as skin, central and peripheral vasculature, and internal organs.

Strategies for efficient resolution analysis in full-waveform inversion

NASA Astrophysics Data System (ADS)

Fichtner, A.; van Leeuwen, T.; Trampert, J.

2016-12-01

Full-waveform inversion is developing into a standard method in the seismological toolbox. It combines numerical wave propagation for heterogeneous media with adjoint techniques in order to improve tomographic resolution. However, resolution becomes increasingly difficult to quantify because of the enormous computational requirements. Here we present two families of methods that can be used for efficient resolution analysis in full-waveform inversion. They are based on the targeted extraction of resolution proxies from the Hessian matrix, which is too large to store and to compute explicitly. Fourier methods rest on the application of the Hessian to Earth models with harmonic oscillations. This yields the Fourier spectrum of the Hessian for few selected wave numbers, from which we can extract properties of the tomographic point-spread function for any point in space. Random probing methods use uncorrelated, random test models instead of harmonic oscillations. Auto-correlating the Hessian-model applications for sufficiently many test models also characterises the point-spread function. Both Fourier and random probing methods provide a rich collection of resolution proxies. These include position- and direction-dependent resolution lengths, and the volume of point-spread functions as indicator of amplitude recovery and inter-parameter trade-offs. The computational requirements of these methods are equivalent to approximately 7 conjugate-gradient iterations in full-waveform inversion. This is significantly less than the optimisation itself, which may require tens to hundreds of iterations to reach convergence. In addition to the theoretical foundations of the Fourier and random probing methods, we show various illustrative examples from real-data full-waveform inversion for crustal and mantle structure.

KiDS-450: cosmological constraints from weak-lensing peak statistics - II: Inference from shear peaks using N-body simulations

NASA Astrophysics Data System (ADS)

Martinet, Nicolas; Schneider, Peter; Hildebrandt, Hendrik; Shan, HuanYuan; Asgari, Marika; Dietrich, Jörg P.; Harnois-Déraps, Joachim; Erben, Thomas; Grado, Aniello; Heymans, Catherine; Hoekstra, Henk; Klaes, Dominik; Kuijken, Konrad; Merten, Julian; Nakajima, Reiko

2018-02-01

We study the statistics of peaks in a weak-lensing reconstructed mass map of the first 450 deg2 of the Kilo Degree Survey (KiDS-450). The map is computed with aperture masses directly applied to the shear field with an NFW-like compensated filter. We compare the peak statistics in the observations with that of simulations for various cosmologies to constrain the cosmological parameter S_8 = σ _8 √{Ω _m/0.3}, which probes the (Ωm, σ8) plane perpendicularly to its main degeneracy. We estimate S8 = 0.750 ± 0.059, using peaks in the signal-to-noise range 0 ≤ S/N ≤ 4, and accounting for various systematics, such as multiplicative shear bias, mean redshift bias, baryon feedback, intrinsic alignment, and shear-position coupling. These constraints are ˜ 25 per cent tighter than the constraints from the high significance peaks alone (3 ≤ S/N ≤ 4) which typically trace single-massive haloes. This demonstrates the gain of information from low-S/N peaks. However, we find that including S/N < 0 peaks does not add further information. Our results are in good agreement with the tomographic shear two-point correlation function measurement in KiDS-450. Combining shear peaks with non-tomographic measurements of the shear two-point correlation functions yields a ˜20 per cent improvement in the uncertainty on S8 compared to the shear two-point correlation functions alone, highlighting the great potential of peaks as a cosmological probe.

Tracking tracer breakthrough in the hyporheic zone using time‐lapse DC resistivity, Crabby Creek, Pennsylvania

USGS Publications Warehouse

Nyquist, Jonathan E.; Toran, Laura; Fang, Allison C.; Ryan, Robert J.; Rosenberry, Donald O.

2010-01-01

Characterization of the hyporheic zone is of critical importance for understanding stream ecology, contaminant transport, and groundwater‐surface water interaction. A salt water tracer test was used to probe the hyporheic zone of a recently re‐engineered portion of Crabby Creek, a stream located near Philadelphia, PA. The tracer solution was tracked through a 13.5 meter segment of the stream using both a network of 25 wells sampled every 5–15 minutes and time‐lapse electrical resistivity tomographs collected every 11 minutes for six hours, with additional tomographs collected every 100 minutes for an additional 16 hours. The comparison of tracer monitoring methods is of keen interest because tracer tests are one of the few techniques available for characterizing this dynamic zone, and logistically it is far easier to collect resistivity tomographs than to install and monitor a dense network of wells. Our results show that resistivity monitoring captured the essential shape of the breakthrough curve and may indicate portions of the stream where the tracer lingered in the hyporheic zone. Time‐lapse resistivity measurements, however, represent time averages over the period required to collect a tomographic data set, and spatial averages over a volume larger than captured by a well sample. Smoothing by the resistivity data inversion algorithm further blurs the resulting tomograph; consequently resistivity monitoring underestimates the degree of fine‐scale heterogeneity in the hyporheic zone.

Field-portable lensfree tomographic microscope†

PubMed Central

Isikman, Serhan O.; Bishara, Waheb; Sikora, Uzair; Yaglidere, Oguzhan; Yeah, John; Ozcan, Aydogan

2011-01-01

We present a field-portable lensfree tomographic microscope, which can achieve sectional imaging of a large volume (~20 mm3) on a chip with an axial resolution of <7 μm. In this compact tomographic imaging platform (weighing only ~110 grams), 24 light-emitting diodes (LEDs) that are each butt-coupled to a fibre-optic waveguide are controlled through a cost-effective micro-processor to sequentially illuminate the sample from different angles to record lensfree holograms of the sample that is placed on the top of a digital sensor array. In order to generate pixel super-resolved (SR) lensfree holograms and hence digitally improve the achievable lateral resolution, multiple sub-pixel shifted holograms are recorded at each illumination angle by electromagnetically actuating the fibre-optic waveguides using compact coils and magnets. These SR projection holograms obtained over an angular range of ~50° are rapidly reconstructed to yield projection images of the sample, which can then be back-projected to compute tomograms of the objects on the sensor-chip. The performance of this compact and light-weight lensfree tomographic microscope is validated by imaging micro-beads of different dimensions as well as a Hymenolepis nana egg, which is an infectious parasitic flatworm. Achieving a decent three-dimensional spatial resolution, this field-portable on-chip optical tomographic microscope might provide a useful toolset for telemedicine and high-throughput imaging applications in resource-poor settings. PMID:21573311

Compressive sensing reconstruction of 3D wet refractivity based on GNSS and InSAR observations

NASA Astrophysics Data System (ADS)

Heublein, Marion; Alshawaf, Fadwa; Erdnüß, Bastian; Zhu, Xiao Xiang; Hinz, Stefan

2018-06-01

In this work, the reconstruction quality of an approach for neutrospheric water vapor tomography based on Slant Wet Delays (SWDs) obtained from Global Navigation Satellite Systems (GNSS) and Interferometric Synthetic Aperture Radar (InSAR) is investigated. The novelties of this approach are (1) the use of both absolute GNSS and absolute InSAR SWDs for tomography and (2) the solution of the tomographic system by means of compressive sensing (CS). The tomographic reconstruction is performed based on (i) a synthetic SWD dataset generated using wet refractivity information from the Weather Research and Forecasting (WRF) model and (ii) a real dataset using GNSS and InSAR SWDs. Thus, the validation of the achieved results focuses (i) on a comparison of the refractivity estimates with the input WRF refractivities and (ii) on radiosonde profiles. In case of the synthetic dataset, the results show that the CS approach yields a more accurate and more precise solution than least squares (LSQ). In addition, the benefit of adding synthetic InSAR SWDs into the tomographic system is analyzed. When applying CS, adding synthetic InSAR SWDs into the tomographic system improves the solution both in magnitude and in scattering. When solving the tomographic system by means of LSQ, no clear behavior is observed. In case of the real dataset, the estimated refractivities of both methodologies show a consistent behavior although the LSQ and CS solution strategies differ.

Investigating Gravity Waves in Polar Mesospheric Clouds Using Tomographic Reconstructions of AIM Satellite Imagery

NASA Astrophysics Data System (ADS)

Hart, V. P.; Taylor, M. J.; Doyle, T. E.; Zhao, Y.; Pautet, P.-D.; Carruth, B. L.; Rusch, D. W.; Russell, J. M.

2018-01-01

This research presents the first application of tomographic techniques for investigating gravity wave structures in polar mesospheric clouds (PMCs) imaged by the Cloud Imaging and Particle Size instrument on the NASA AIM satellite. Albedo data comprising consecutive PMC scenes were used to tomographically reconstruct a 3-D layer using the Partially Constrained Algebraic Reconstruction Technique algorithm and a previously developed "fanning" technique. For this pilot study, a large region (760 × 148 km) of the PMC layer (altitude 83 km) was sampled with a 2 km horizontal resolution, and an intensity weighted centroid technique was developed to create novel 2-D surface maps, characterizing the individual gravity waves as well as their altitude variability. Spectral analysis of seven selected wave events observed during the Northern Hemisphere 2007 PMC season exhibited dominant horizontal wavelengths of 60-90 km, consistent with previous studies. These tomographic analyses have enabled a broad range of new investigations. For example, a clear spatial anticorrelation was observed between the PMC albedo and wave-induced altitude changes, with higher-albedo structures aligning well with wave troughs, while low-intensity regions aligned with wave crests. This result appears to be consistent with current theories of PMC development in the mesopause region. This new tomographic imaging technique also provides valuable wave amplitude information enabling further mesospheric gravity wave investigations, including quantitative analysis of their hemispheric and interannual characteristics and variations.

Position-specific incorporation of fluorescent non-natural amino acids into maltose-binding protein for detection of ligand binding by FRET and fluorescence quenching.

PubMed

Iijima, Issei; Hohsaka, Takahiro

2009-04-17

Position-specific incorporation of fluorescent groups is a useful method for analysis of the functions and structures of proteins. We have developed a method for the incorporation of visible-wavelength-fluorescent non-natural amino acids into proteins in a cell-free translation system. Using this technique, we introduced one or two BODIPY-linked amino acids into maltose-binding protein (MBP) to obtain MBP derivatives showing ligand-dependent changes in fluorescence intensity or intensity ratio. BODIPY-FL-aminophenylalanine was incorporated in place of 15 tyrosines, as well as the N-terminal Lys1, and the C-terminal Lys370 of MBP. Fluorescence measurements revealed that MBP containing a BODIPY-FL moiety in place of Tyr210 showed a 13-fold increase in fluorescence upon binding of maltose. Tryptophan-to-phenylalanine substitutions suggest that the increase in fluorescence was the result of a decrease in the quenching of BODIPY-FL by tryptophan located around the binding site. MBP containing a BODIPY-558 moiety also showed a maltose-dependent increase in fluorescence. BODIPY-FL was then additionally incorporated in place of Lys1 of the BODIPY-558-containing MBP as a response to the amber codon. Fluorescence measurements with excitation of BODIPY-FL showed a large change in fluorescence intensity ratio (0.13 to 1.25) upon binding of maltose; this change can be attributed to fluorescence resonance energy transfer (FRET) and maltose-dependent quenching of BODIPY-558. These results demonstrate the usefulness of the position-specific incorporation of fluorescent amino acids in the fluorescence-based detection of protein functions.

Quantifying cadherin mechanotransduction machinery assembly/disassembly dynamics using fluorescence covariance analysis.

PubMed

Vedula, Pavan; Cruz, Lissette A; Gutierrez, Natasha; Davis, Justin; Ayee, Brian; Abramczyk, Rachel; Rodriguez, Alexis J

2016-06-30

Quantifying multi-molecular complex assembly in specific cytoplasmic compartments is crucial to understand how cells use assembly/disassembly of these complexes to control function. Currently, biophysical methods like Fluorescence Resonance Energy Transfer and Fluorescence Correlation Spectroscopy provide quantitative measurements of direct protein-protein interactions, while traditional biochemical approaches such as sub-cellular fractionation and immunoprecipitation remain the main approaches used to study multi-protein complex assembly/disassembly dynamics. In this article, we validate and quantify multi-protein adherens junction complex assembly in situ using light microscopy and Fluorescence Covariance Analysis. Utilizing specific fluorescently-labeled protein pairs, we quantified various stages of adherens junction complex assembly, the multiprotein complex regulating epithelial tissue structure and function following de novo cell-cell contact. We demonstrate: minimal cadherin-catenin complex assembly in the perinuclear cytoplasm and subsequent localization to the cell-cell contact zone, assembly of adherens junction complexes, acto-myosin tension-mediated anchoring, and adherens junction maturation following de novo cell-cell contact. Finally applying Fluorescence Covariance Analysis in live cells expressing fluorescently tagged adherens junction complex proteins, we also quantified adherens junction complex assembly dynamics during epithelial monolayer formation.

FluoroSim: A Visual Problem-Solving Environment for Fluorescence Microscopy

PubMed Central

Quammen, Cory W.; Richardson, Alvin C.; Haase, Julian; Harrison, Benjamin D.; Taylor, Russell M.; Bloom, Kerry S.

2010-01-01

Fluorescence microscopy provides a powerful method for localization of structures in biological specimens. However, aspects of the image formation process such as noise and blur from the microscope's point-spread function combine to produce an unintuitive image transformation on the true structure of the fluorescing molecules in the specimen, hindering qualitative and quantitative analysis of even simple structures in unprocessed images. We introduce FluoroSim, an interactive fluorescence microscope simulator that can be used to train scientists who use fluorescence microscopy to understand the artifacts that arise from the image formation process, to determine the appropriateness of fluorescence microscopy as an imaging modality in an experiment, and to test and refine hypotheses of model specimens by comparing the output of the simulator to experimental data. FluoroSim renders synthetic fluorescence images from arbitrary geometric models represented as triangle meshes. We describe three rendering algorithms on graphics processing units for computing the convolution of the specimen model with a microscope's point-spread function and report on their performance. We also discuss several cases where the microscope simulator has been used to solve real problems in biology. PMID:20431698

Fluorescent Nanodiamonds in Biomedical Applications.

PubMed

Mitura, Katarzyna Anna; Włodarczyk, Elżbieta

2018-04-18

Nanoparticles have an extended surface and a large surface area, which is the ratio of the size of the surfacearea to the volume. A functionalized surface can give rise to more modifications and therefore allows this nanomaterial to have new properties. Fluorescent molecules contain fluorophore, which is capable of being excited via the absorption of light energy at a specific wavelength and subsequently emitting radiation energy of a longer wavelength. A chemically modified surface of nanodiamond (ND; by carboxylation) demonstrated biocompatibility with DNA, cytochrome C, and antigens. In turn, fluorescent nanodiamonds (FNDs) belong to a group of new nanomaterials. Their surface can be modified by joining functional groups such as carboxyl, hydroxyl, or amino, after which they can be employed as a fluorescence agent. Their fluorescent properties result from defects in the crystal lattice. FNDs reach dimensions of 4-100 nm, have attributes such as photostability, long fluorescence lifetimes (10 ns), and fluorescence emission between 600 and 700 nm. They are also nontoxic, chemically inert, biocompatible, and environmentally harmless. The main purpose of this article was to present the medical applications of various types of modified NDs.

Expression of fluorescently tagged connexins: a novel approach to rescue function of oligomeric DsRed-tagged proteins.

PubMed

Lauf, U; Lopez, P; Falk, M M

2001-06-01

A novel, brilliantly red fluorescent protein, DsRed has become available recently opening up a wide variety of experimental opportunities for double labeling and fluorescence resonance electron transfer experiments in combination with green fluorescent protein (GFP). Unlike in the case of GFP, proteins tagged with DsRed were often found to aggregate within the cell. Here we report a simple method that allows rescuing the function of an oligomeric protein tagged with DsRed. We demonstrate the feasibility of this approach on the subunit proteins of an oligomeric membrane channel, gap junction connexins. Additionally, DsRed fluorescence was easily detected 12-16 h post transfection, much earlier than previously reported, and could readily be differentiated from co-expressed GFP. Thus, this approach can eliminate the major drawbacks of this highly attractive autofluorescent protein.

A practical teaching course in directed protein evolution using the green fluorescent protein as a model.

PubMed

Ruller, Roberto; Silva-Rocha, Rafael; Silva, Artur; Cruz Schneider, Maria Paula; Ward, Richard John

2011-01-01

Protein engineering is a powerful tool, which correlates protein structure with specific functions, both in applied biotechnology and in basic research. Here, we present a practical teaching course for engineering the green fluorescent protein (GFP) from Aequorea victoria by a random mutagenesis strategy using error-prone polymerase chain reaction. Screening of bacterial colonies transformed with random mutant libraries identified GFP variants with increased fluorescence yields. Mapping the three-dimensional structure of these mutants demonstrated how alterations in structural features such as the environment around the fluorophore and properties of the protein surface can influence functional properties such as the intensity of fluorescence and protein solubility. Copyright © 2011 Wiley Periodicals, Inc.

Application Of Iterative Reconstruction Techniques To Conventional Circular Tomography

NASA Astrophysics Data System (ADS)

Ghosh Roy, D. N.; Kruger, R. A.; Yih, B. C.; Del Rio, S. P.; Power, R. L.

1985-06-01

Two "point-by-point" iteration procedures, namely, Iterative Least Square Technique (ILST) and Simultaneous Iterative Reconstructive Technique (SIRT) were applied to classical circular tomographic reconstruction. The technique of tomosynthetic DSA was used in forming the tomographic images. Reconstructions of a dog's renal and neck anatomy are presented.

21 CFR 892.1740 - Tomographic x-ray system.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Tomographic x-ray system. 892.1740 Section 892.1740 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED.... This generic type of device may include signal analysis and display equipment, patient and equipment...

21 CFR 892.1740 - Tomographic x-ray system.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Tomographic x-ray system. 892.1740 Section 892.1740 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED.... This generic type of device may include signal analysis and display equipment, patient and equipment...

21 CFR 892.1740 - Tomographic x-ray system.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Tomographic x-ray system. 892.1740 Section 892.1740 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED.... This generic type of device may include signal analysis and display equipment, patient and equipment...

21 CFR 892.1740 - Tomographic x-ray system.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Tomographic x-ray system. 892.1740 Section 892.1740 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED.... This generic type of device may include signal analysis and display equipment, patient and equipment...

21 CFR 892.1740 - Tomographic x-ray system.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Tomographic x-ray system. 892.1740 Section 892.1740 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED.... This generic type of device may include signal analysis and display equipment, patient and equipment...

ECAT: A New Computerized Tomographic Imaging System for Position-Emitting Radiopharmaceuticals

DOE R&D Accomplishments Database

Phelps, M. E.; Hoffman, E. J.; Huang, S. C.; Kuhl, D. E.

1977-01-01

The ECAT was designed and developed as a complete computerized positron radionuclide imaging system capable of providing high contrast, high resolution, quantitative images in 2 dimensional and tomographic formats. Flexibility, in its various image mode options, allows it to be used for a wide variety of imaging problems.

[Rapid identification of hogwash oil by using synchronous fluorescence spectroscopy].

PubMed

Sun, Yan-Hui; An, Hai-Yang; Jia, Xiao-Li; Wang, Juan

2012-10-01

To identify hogwash oil quickly, the characteristic delta lambda of hogwash oil was analyzed by three dimensional fluorescence spectroscopy with parallel factor analysis, and the model was built up by using synchronous fluorescence spectroscopy with support vector machines (SVM). The results showed that the characteristic delta lambda of hogwash oil was 60 nm. Collecting original spectrum of different samples under the condition of characteristic delta lambda 60 nm, the best model was established while 5 principal components were selected from original spectrum and the radial basis function (RBF) was used as the kernel function, and the optimal penalty factor C and kernel function g were 512 and 0.5 respectively obtained by the grid searching and 6-fold cross validation. The discrimination rate of the model was 100% for both training sets and prediction sets. Thus, it is quick and accurate to apply synchronous fluorescence spectroscopy to identification of hogwash oil.

New hexa-bodipy functionalized dendrimeric cyclotriphosphazene conjugates as highly selective and sensitive fluorescent chemosensor for Co2+ ions

NASA Astrophysics Data System (ADS)

Şenkuytu, Elif; Tanrıverdi Eçik, Esra

2018-06-01

In the study, the new hexa-bodipy functionalized dendrimeric cyclotriphosphazene conjugates (HBCP 1 and 2) have been successfully synthesized and characterized by using general spectroscopic techniques such as 1H, 13C and 31P NMR spectroscopies. The photophysical and metal sensing properties in THF solutions of dendrimeric cyclotriphosphazene conjugates (HBCP 1 and 2) were investigated by UV-Vis and fluorescence spectroscopies in dilute tetrahydrofuran solutions. These dendrimers showed strong absorption bands 501 and 641 nm at low concentration with high molar extinction coefficients. In addition, the stoichiometry of the complex between the conjugate (HBCP 2) and Co2+ ions were determined by a Job's plot obtained from fluorescence titrations. The metal sensing data showed that the hexa-bodipy functionalized dendrimeric cyclotriphosphazene conjugate (HBCP 2) is a candidate for fluorescent chemosensor for Co2+ ions due to showing high selectivity with a low limit of detection.

Fluorescent Labeling and Biodistribution of Latex Nanoparticles Formed by Surfactant-Free RAFT Emulsion Polymerization.

PubMed

Poon, Cheuk Ka; Tang, Owen; Chen, Xin-Ming; Kim, Byung; Hartlieb, Matthias; Pollock, Carol A; Hawkett, Brian S; Perrier, Sébastien

2017-10-01

The authors report the preparation of a novel range of functional polyacrylamide stabilized polystyrene nanoparticles, obtained by surfactant-free reversible addition-fragmentation chain transfer (RAFT) emulsion polymerization, their fluorescent tagging, cellular uptake, and biodistribution. The authors show the versatility of the RAFT emulsion process for the design of functional nanoparticles of well-defined size that can be used as drug delivery vectors. Functionalization with a fluorescent tag offers a useful visualization tool for tracing, localization, and clearance studies of these carriers in biological models. The studies are carried out by labeling the sterically stabilized latex particles chemically with rhodamine B. The fluorescent particles are incubated in a healthy human renal proximal tubular cell line model, and intravenously injected into a mouse model. Cellular localization and biodistribution of these particles on the biological models are explored. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Reaction-based small-molecule fluorescent probes for dynamic detection of ROS and transient redox changes in living cells and small animals.

PubMed

Lü, Rui

2017-09-01

Dynamic detection of transient redox changes in living cells and animals has broad implications for human health and disease diagnosis, because intracellular redox homeostasis regulated by reactive oxygen species (ROS) plays important role in cell functions, normal physiological functions and some serious human diseases (e.g., cancer, Alzheimer's disease, diabetes, etc.) usually have close relationship with the intracellular redox status. Small-molecule ROS-responsive fluorescent probes can act as powerful tools for dynamic detection of ROS and redox changes in living cells and animals through fluorescence imaging techniques; and great advances have been achieved recently in the design and synthesis of small-molecule ROS-responsive fluorescent probes. This article highlights up-to-date achievements in designing and using the reaction-based small-molecule fluorescent probes (with high sensitivity and selectivity to ROS and redox cycles) in the dynamic detection of ROS and transient redox changes in living cells and animals through fluorescence imaging. Copyright © 2017. Published by Elsevier Ltd.

Pseudolocal tomography

DOEpatents

Katsevich, Alexander J.; Ramm, Alexander G.

1996-01-01

Local tomographic data is used to determine the location and value of a discontinuity between a first internal density of an object and a second density of a region within the object. A beam of radiation is directed in a predetermined pattern through the region of the object containing the discontinuity. Relative attenuation data of the beam is determined within the predetermined pattern having a first data component that includes attenuation data through the region. The relative attenuation data is input to a pseudo-local tomography function, where the difference between the internal density and the pseudo-local tomography function is computed across the discontinuity. The pseudo-local tomography function outputs the location of the discontinuity and the difference in density between the first density and the second density.

Pseudolocal tomography

DOEpatents

Katsevich, A.J.; Ramm, A.G.

1996-07-23

Local tomographic data is used to determine the location and value of a discontinuity between a first internal density of an object and a second density of a region within the object. A beam of radiation is directed in a predetermined pattern through the region of the object containing the discontinuity. Relative attenuation data of the beam is determined within the predetermined pattern having a first data component that includes attenuation data through the region. The relative attenuation data is input to a pseudo-local tomography function, where the difference between the internal density and the pseudo-local tomography function is computed across the discontinuity. The pseudo-local tomography function outputs the location of the discontinuity and the difference in density between the first density and the second density. 7 figs.

Including Short Period Constraints In the Construction of Full Waveform Tomographic Models

NASA Astrophysics Data System (ADS)

Roy, C.; Calo, M.; Bodin, T.; Romanowicz, B. A.

2015-12-01

Thanks to the introduction of the Spectral Element Method (SEM) in seismology, which allows accurate computation of the seismic wavefield in complex media, the resolution of regional and global tomographic models has improved in recent years. However, due to computational costs, only long period waveforms are considered, and only long wavelength structure can be constrained. Thus, the resulting 3D models are smooth, and only represent a small volumetric perturbation around a smooth reference model that does not include upper-mantle discontinuities (e.g. MLD, LAB). Extending the computations to shorter periods, necessary for the resolution of smaller scale features, is computationally challenging. In order to overcome these limitations and to account for layered structure in the upper mantle in our full waveform tomography, we include information provided by short period seismic observables (receiver functions and surface wave dispersion), sensitive to sharp boundaries and anisotropic structure respectively. In a first step, receiver functions and dispersion curves are used to generate a number of 1D radially anisotropic shear velocity profiles using a trans-dimensional Markov-chain Monte Carlo (MCMC) algorithm. These 1D profiles include both isotropic and anisotropic discontinuities in the upper mantle (above 300 km depth) beneath selected stationsand are then used to build a 3D starting model for the full waveform tomographic inversion. This model is built after 1) interpolation between the available 1D profiles, and 2) homogeneization of the layered 1D models to obtain an equivalent smooth 3D starting model in the period range of interest for waveform inversion. The waveforms used in the inversion are collected for paths contained in the region of study and filtered at periods longer than 40s. We use the spectral element code "RegSEM" (Cupillard et al., 2012) for forward computations and a quasi-Newton inversion approach in which kernels are computed using normal mode perturbation theory. We present here the first reults of such an approach after successive iterations of a full waveform tomography of the North American continent.

Morphological and functional changes in TRPM8-expressing corneal cold thermoreceptor neurons during aging and their impact on tearing in mice.

PubMed

Alcalde, Ignacio; Íñigo-Portugués, Almudena; González-González, Omar; Almaraz, Laura; Artime, Enol; Morenilla-Palao, Cruz; Gallar, Juana; Viana, Félix; Merayo-Lloves, Jesús; Belmonte, Carlos

2018-08-01

Morphological and functional alterations of peripheral somatosensory neurons during the aging process lead to a decline of somatosensory perception. Here, we analyze the changes occurring with aging in trigeminal ganglion (TG), TRPM8-expressing cold thermoreceptor neurons innervating the mouse cornea, which participate in the regulation of basal tearing and blinking and have been implicated in the pathogenesis of dry eye disease (DED). TG cell bodies and axonal branches were examined in a mouse line (TRPM8 BAC -EYFP) expressing a fluorescent reporter. In 3 months old animals, about 50% of TG cold thermoreceptor neurons were intensely fluorescent, likely providing strongly fluorescent axons and complex corneal nerve terminals with ongoing activity at 34°C and low-threshold, robust responses to cooling. The remaining TRPM8 + corneal axons were weakly fluorescent with nonbeaded axons, sparsely ramified nerve terminals, and exhibited a low-firing rate at 34°C, responding moderately to cooling pulses as do weakly fluorescent TG neurons. In aged (24 months) mice, the number of weakly fluorescent TG neurons was strikingly high while the morphology of TRPM8 + corneal axons changed drastically; 89% were weakly fluorescent, unbranched, and often ending in the basal epithelium. Functionally, 72.5% of aged cold terminals responded as those of young animals, but 27.5% exhibited very low-background activity and abnormal responsiveness to cooling pulses. These morpho-functional changes develop in parallel with an enhancement of tear's basal flow and osmolarity, suggesting that the aberrant sensory inflow to the brain from impaired peripheral cold thermoreceptors contributes to age-induced abnormal tearing and to the high incidence of DED in elderly people. © 2018 Wiley Periodicals, Inc.

Modeling of transdermal fluorescence measurements from first-in-human clinical trials for renal function determination using fluorescent tracer agent MB-102

NASA Astrophysics Data System (ADS)

Shultz, Kimberly M.; Debreczeny, Martin P.; Dorshow, Richard B.; Keating, Jennifer E.; Bechtel, Kate L.

2017-02-01

The fluorescent tracer agent 3,6-diamino-2,5-bisN-[(1R)-1-carboxy-2-hydroxyethyl]carbamoylpyrazine, designated MB-102, is cleared from the body solely by the kidneys. A prototype noninvasive fluorescence detection device has been developed for monitoring transdermal fluorescence after bolus intravenous injection of MB-102 in order to measure kidney function. A mathematical model of the detected fluorescence signal was created for evaluation of observed variations in agent kinetics across body locations and for analysis of candidate instrument geometries. The model comprises pharmacokinetics of agent distribution within body compartments, local diffusion of the agent within the skin, Monte Carlo photon transport through tissue, and ray tracing of the instrument optics. Data from eight human subjects with normal renal function and a range of skin colors shows good agreement with simulated data. Body site dependence of equilibration kinetics was explored using the model to find the local vasculature-to-interstitial diffusion time constant, blood volume fraction, and interstitial volume fraction. Finally, candidate instrument geometries were evaluated using the model. While an increase in source-detector separation was found to increase sensitivity to tissue optical properties, it reduced the relative intensity of the background signal with minimal effect on the measured equilibration kinetics.

APTS and rGO co-functionalized pyrenated fluorescent nanonets for representative vapor phase nitroaromatic explosive detection

NASA Astrophysics Data System (ADS)

Guo, Linjuan; Zu, Baiyi; Yang, Zheng; Cao, Hongyu; Zheng, Xuefang; Dou, Xincun

2014-01-01

For the first time, flexible PVP/pyrene/APTS/rGO fluorescent nanonets were designed and synthesized via a one-step electrospinning method to detect representative subsaturated nitroaromatic explosive vapor. The functional fluorescent nanonets, which were highly stable in air, showed an 81% quenching efficiency towards TNT vapor (~10 ppb) with an exposure time of 540 s at room temperature. The nice performance of the nanonets was ascribed to the synergistic effects induced by the specific adsorption properties of APTS, the fast charge transfer properties and the effective π-π interaction with pyrene and TNT of rGO. Compared to the analogues of TNT, the PVP/pyrene/APTS/rGO nanonets showed notable selectivity towards TNT and DNT vapors. The explored functionalization method opens up brand new insight into sensitive and selective detection of vapor phase nitroaromatic explosives.For the first time, flexible PVP/pyrene/APTS/rGO fluorescent nanonets were designed and synthesized via a one-step electrospinning method to detect representative subsaturated nitroaromatic explosive vapor. The functional fluorescent nanonets, which were highly stable in air, showed an 81% quenching efficiency towards TNT vapor (~10 ppb) with an exposure time of 540 s at room temperature. The nice performance of the nanonets was ascribed to the synergistic effects induced by the specific adsorption properties of APTS, the fast charge transfer properties and the effective π-π interaction with pyrene and TNT of rGO. Compared to the analogues of TNT, the PVP/pyrene/APTS/rGO nanonets showed notable selectivity towards TNT and DNT vapors. The explored functionalization method opens up brand new insight into sensitive and selective detection of vapor phase nitroaromatic explosives. Electronic supplementary information (ESI) available: Vapor pressure of TNT and its analogues, fluorescence quenching kinetics, fluorescence quenching efficiencies and additional SEM images. See DOI: 10.1039/c3nr04960d

Uncertainty loops in travel-time tomography from nonlinear wave physics.

PubMed

Galetti, Erica; Curtis, Andrew; Meles, Giovanni Angelo; Baptie, Brian

2015-04-10

Estimating image uncertainty is fundamental to guiding the interpretation of geoscientific tomographic maps. We reveal novel uncertainty topologies (loops) which indicate that while the speeds of both low- and high-velocity anomalies may be well constrained, their locations tend to remain uncertain. The effect is widespread: loops dominate around a third of United Kingdom Love wave tomographic uncertainties, changing the nature of interpretation of the observed anomalies. Loops exist due to 2nd and higher order aspects of wave physics; hence, although such structures must exist in many tomographic studies in the physical sciences and medicine, they are unobservable using standard linearized methods. Higher order methods might fruitfully be adopted.

Tomographic diffractive microscopy with a wavefront sensor.

PubMed

Ruan, Y; Bon, P; Mudry, E; Maire, G; Chaumet, P C; Giovannini, H; Belkebir, K; Talneau, A; Wattellier, B; Monneret, S; Sentenac, A

2012-05-15

Tomographic diffractive microscopy is a recent imaging technique that reconstructs quantitatively the three-dimensional permittivity map of a sample with a resolution better than that of conventional wide-field microscopy. Its main drawbacks lie in the complexity of the setup and in the slowness of the image recording as both the amplitude and the phase of the field scattered by the sample need to be measured for hundreds of successive illumination angles. In this Letter, we show that, using a wavefront sensor, tomographic diffractive microscopy can be implemented easily on a conventional microscope. Moreover, the number of illuminations can be dramatically decreased if a constrained reconstruction algorithm is used to recover the sample map of permittivity.

Tomographic and analog 3-D simulations using NORA. [Non-Overlapping Redundant Image Array formed by multiple pinholes

NASA Technical Reports Server (NTRS)

Yin, L. I.; Trombka, J. I.; Bielefeld, M. J.; Seltzer, S. M.

1984-01-01

The results of two computer simulations demonstrate the feasibility of using the nonoverlapping redundant array (NORA) to form three-dimensional images of objects with X-rays. Pinholes admit the X-rays to nonoverlapping points on a detector. The object is reconstructed in the analog mode by optical correlation and in the digital mode by tomographic computations. Trials were run with a stick-figure pyramid and extended objects with out-of-focus backgrounds. Substitution of spherical optical lenses for the pinholes increased the light transmission sufficiently that objects could be easily viewed in a dark room. Out-of-focus aberrations in tomographic reconstruction could be eliminated using Chang's (1976) algorithm.

Tomographic phase microscopy: principles and applications in bioimaging [Invited

PubMed Central

Jin, Di; Zhou, Renjie; Yaqoob, Zahid; So, Peter T. C.

2017-01-01

Tomographic phase microscopy (TPM) is an emerging optical microscopic technique for bioimaging. TPM uses digital holographic measurements of complex scattered fields to reconstruct three-dimensional refractive index (RI) maps of cells with diffraction-limited resolution by solving inverse scattering problems. In this paper, we review the developments of TPM from the fundamental physics to its applications in bioimaging. We first provide a comprehensive description of the tomographic reconstruction physical models used in TPM. The RI map reconstruction algorithms and various regularization methods are discussed. Selected TPM applications for cellular imaging, particularly in hematology, are reviewed. Finally, we examine the limitations of current TPM systems, propose future solutions, and envision promising directions in biomedical research. PMID:29386746

MicroCT with energy-resolved photon-counting detectors

PubMed Central

Wang, X; Meier, D; Mikkelsen, S; Maehlum, G E; Wagenaar, D J; Tsui, BMW; Patt, B E; Frey, E C

2011-01-01

The goal of this paper was to investigate the benefits that could be realistically achieved on a microCT imaging system with an energy-resolved photon-counting x-ray detector. To this end, we built and evaluated a prototype microCT system based on such a detector. The detector is based on cadmium telluride (CdTe) radiation sensors and application-specific integrated circuit (ASIC) readouts. Each detector pixel can simultaneously count x-ray photons above six energy thresholds, providing the capability for energy-selective x-ray imaging. We tested the spectroscopic performance of the system using polychromatic x-ray radiation and various filtering materials with Kabsorption edges. Tomographic images were then acquired of a cylindrical PMMA phantom containing holes filled with various materials. Results were also compared with those acquired using an intensity-integrating x-ray detector and single-energy (i.e. non-energy-selective) CT. This paper describes the functionality and performance of the system, and presents preliminary spectroscopic and tomographic results. The spectroscopic experiments showed that the energy-resolved photon-counting detector was capable of measuring energy spectra from polychromatic sources like a standard x-ray tube, and resolving absorption edges present in the energy range used for imaging. However, the spectral quality was degraded by spectral distortions resulting from degrading factors, including finite energy resolution and charge sharing. We developed a simple charge-sharing model to reproduce these distortions. The tomographic experiments showed that the availability of multiple energy thresholds in the photon-counting detector allowed us to simultaneously measure target-to-background contrasts in different energy ranges. Compared with single-energy CT with an integrating detector, this feature was especially useful to improve differentiation of materials with different attenuation coefficient energy dependences. PMID:21464527

A 3D tomographic reconstruction method to analyze Jupiter's electron-belt emission observations

NASA Astrophysics Data System (ADS)

Santos-Costa, Daniel; Girard, Julien; Tasse, Cyril; Zarka, Philippe; Kita, Hajime; Tsuchiya, Fuminori; Misawa, Hiroaki; Clark, George; Bagenal, Fran; Imai, Masafumi; Becker, Heidi N.; Janssen, Michael A.; Bolton, Scott J.; Levin, Steve M.; Connerney, John E. P.

2017-04-01

Multi-dimensional reconstruction techniques of Jupiter's synchrotron radiation from radio-interferometric observations were first developed by Sault et al. [Astron. Astrophys., 324, 1190-1196, 1997]. The tomographic-like technique introduced 20 years ago had permitted the first 3-dimensional mapping of the brightness distribution around the planet. This technique has demonstrated the advantage to be weakly dependent on planetary field models. It also does not require any knowledge on the energy and spatial distributions of the radiating electrons. On the downside, it is assumed that the volume emissivity of any punctual point source around the planet is isotropic. This assumption becomes incorrect when mapping the brightness distribution for non-equatorial point sources or any point sources from Juno's perspective. In this paper, we present our modeling effort to bypass the isotropy issue. Our approach is to use radio-interferometric observations and determine the 3-D brightness distribution in a cylindrical coordinate system. For each set (z, r), we constrain the longitudinal distribution with a Fourier series and the anisotropy is addressed with a simple periodic function when possible. We develop this new method over a wide range of frequencies using past VLA and LOFAR observations of Jupiter. We plan to test this reconstruction method with observations of Jupiter that are currently being carried out with LOFAR and GMRT in support to the Juno mission. We describe how this new 3D tomographic reconstruction method provides new model constraints on the energy and spatial distributions of Jupiter's ultra-relativistic electrons close to the planet and be used to interpret Juno MWR observations of Jupiter's electron-belt emission and assist in evaluating the background noise from the radiation environment in the atmospheric measurements.

MicroCT with energy-resolved photon-counting detectors.

PubMed

Wang, X; Meier, D; Mikkelsen, S; Maehlum, G E; Wagenaar, D J; Tsui, B M W; Patt, B E; Frey, E C

2011-05-07

The goal of this paper was to investigate the benefits that could be realistically achieved on a microCT imaging system with an energy-resolved photon-counting x-ray detector. To this end, we built and evaluated a prototype microCT system based on such a detector. The detector is based on cadmium telluride (CdTe) radiation sensors and application-specific integrated circuit (ASIC) readouts. Each detector pixel can simultaneously count x-ray photons above six energy thresholds, providing the capability for energy-selective x-ray imaging. We tested the spectroscopic performance of the system using polychromatic x-ray radiation and various filtering materials with K-absorption edges. Tomographic images were then acquired of a cylindrical PMMA phantom containing holes filled with various materials. Results were also compared with those acquired using an intensity-integrating x-ray detector and single-energy (i.e. non-energy-selective) CT. This paper describes the functionality and performance of the system, and presents preliminary spectroscopic and tomographic results. The spectroscopic experiments showed that the energy-resolved photon-counting detector was capable of measuring energy spectra from polychromatic sources like a standard x-ray tube, and resolving absorption edges present in the energy range used for imaging. However, the spectral quality was degraded by spectral distortions resulting from degrading factors, including finite energy resolution and charge sharing. We developed a simple charge-sharing model to reproduce these distortions. The tomographic experiments showed that the availability of multiple energy thresholds in the photon-counting detector allowed us to simultaneously measure target-to-background contrasts in different energy ranges. Compared with single-energy CT with an integrating detector, this feature was especially useful to improve differentiation of materials with different attenuation coefficient energy dependences.

Four-dimensional in vivo X-ray microscopy with projection-guided gating

NASA Astrophysics Data System (ADS)

Mokso, Rajmund; Schwyn, Daniel A.; Walker, Simon M.; Doube, Michael; Wicklein, Martina; Müller, Tonya; Stampanoni, Marco; Taylor, Graham K.; Krapp, Holger G.

2015-03-01

Visualizing fast micrometer scale internal movements of small animals is a key challenge for functional anatomy, physiology and biomechanics. We combine phase contrast tomographic microscopy (down to 3.3 μm voxel size) with retrospective, projection-based gating (in the order of hundreds of microseconds) to improve the spatiotemporal resolution by an order of magnitude over previous studies. We demonstrate our method by visualizing 20 three-dimensional snapshots through the 150 Hz oscillations of the blowfly flight motor.

Model studies of laser absorption computed tomography for remote air pollution measurement

NASA Technical Reports Server (NTRS)

Wolfe, D. C., Jr.; Byer, R. L.

1982-01-01

Model studies of the potential of laser absorption-computed tomography are presented which demonstrate the possibility of sensitive remote atmospheric pollutant measurements, over kilometer-sized areas, with two-dimensional resolution, at modest laser source powers. An analysis of this tomographic reconstruction process as a function of measurement SNR, laser power, range, and system geometry, shows that the system is able to yield two-dimensional maps of pollutant concentrations at ranges and resolutions superior to those attainable with existing, direct-detection laser radars.

Development of dansyl-modified oligonucleotide probes responding to structural changes in a duplex.

PubMed

Suzuki, Yoshio; Kowata, Keiko; Komatsu, Yasuo

2013-11-15

We have synthesized a nonnucleoside amidite block of dansyl fluorophore to prepare dansyl-modified oligonucleotides (ONTs). The fluorescence intensities of dansyl-ONT specifically increased by the presence of adjacent guanosine residues but, significantly reduced in a dansyl-flipping duplex. These changes were caused by solvatochromism effect due to the number of guanine which is hydrophobic functional group and the external environment of dansyl group. The fluorescence intensities could be plotted as a function of the ONTs concentrations and the increase in the fluorescence was observed to equimolar concentrations of target DNA. This duplex exhibited higher melting temperature relative to the corresponding duplexes containing other base pairs. Similar changes in fluorescence could be detected upon hybridization with complementary RNAs. Thus, the dansyl-modified ONTs provide sequence specific fluorescent probe of DNA and RNA. Copyright © 2013 Elsevier Ltd. All rights reserved.

[Visualization and Functional Regulation of Live Cell Proteins Based on Labeling Probe Design].

PubMed

Mizukami, Shin; Kikuchi, Kazuya

2016-01-01

  There are several approaches to understanding the physiological roles of biomolecules: (1) by observing the localization or activities of biomolecules (based on microscopic imaging experiments with fluorescent proteins or fluorescent probes) and (2) by investigating the cellular response via activation or suppression of functions of the target molecule (by using inhibitors, antagonists, siRNAs, etc.). In this context, protein-labeling technology serves as a powerful tool that can be used in various experiments, such as for fluorescence imaging of target proteins. Recently, we developed a protein-labeling technology that uses a mutant β-lactamase (a bacterial hydrolase) as the tag protein. In this protein-labeling technology, also referred to as the BL-tag technology, various β-lactam compounds were used as specific ligands that were covalently labeled to the tag. One major advantage of this labeling technology is that various functions can be carried out by suitably designing both the functional moieties such as the fluorophore and the β-lactam ligand structure. In this review, we briefly introduce the BL-tag technology and describe our future outlook for this technology, such as in fluorescence imaging of biomolecules and functional regulation of cellular proteins in living cells.

Developing a novel fiber optic fluorescence device for multiplexed high-throughput cytotoxic screening.

PubMed

Lee, Dennis; Barnes, Stephen

2010-01-01

The need for new pharmacological agents is unending. Yet the drug discovery process has changed substantially over the past decade and continues to evolve in response to new technologies. There is presently a high demand to reduce discovery time by improving specific lab disciplines and developing new technology platforms in the area of cell-based assay screening. Here we present the developmental concept and early stage testing of the Ab-Sniffer, a novel fiber optic fluorescence device for high-throughput cytotoxicity screening using an immobilized whole cell approach. The fused silica fibers are chemically functionalized with biotin to provide interaction with fluorescently labeled, streptavidin functionalized alginate-chitosan microspheres. The microspheres are also functionalized with Concanavalin A to facilitate binding to living cells. By using lymphoma cells and rituximab in an adaptation of a well-known cytotoxicity protocol we demonstrate the utility of the Ab-Sniffer for functional screening of potential drug compounds rather than indirect, non-functional screening via binding assay. The platform can be extended to any assay capable of being tied to a fluorescence response including multiple target cells in each well of a multi-well plate for high-throughput screening.

Efficient switching of mCherry fluorescence using chemical caging.

PubMed

Cloin, Bas M C; De Zitter, Elke; Salas, Desiree; Gielen, Vincent; Folkers, Gert E; Mikhaylova, Marina; Bergeler, Maike; Krajnik, Bartosz; Harvey, Jeremy; Hoogenraad, Casper C; Van Meervelt, Luc; Dedecker, Peter; Kapitein, Lukas C

2017-07-03

Fluorophores with dynamic or controllable fluorescence emission have become essential tools for advanced imaging, such as superresolution imaging. These applications have driven the continuing development of photoactivatable or photoconvertible labels, including genetically encoded fluorescent proteins. These new probes work well but require the introduction of new labels that may interfere with the proper functioning of existing constructs and therefore require extensive functional characterization. In this work we show that the widely used red fluorescent protein mCherry can be brought to a purely chemically induced blue-fluorescent state by incubation with β-mercaptoethanol (βME). The molecules can be recovered to the red fluorescent state by washing out the βME or through irradiation with violet light, with up to 80% total recovery. We show that this can be used to perform single-molecule localization microscopy (SMLM) on cells expressing mCherry, which renders this approach applicable to a very wide range of existing constructs. We performed a detailed investigation of the mechanism underlying these dynamics, using X-ray crystallography, NMR spectroscopy, and ab initio quantum-mechanical calculations. We find that the βME-induced fluorescence quenching of mCherry occurs both via the direct addition of βME to the chromophore and through βME-mediated reduction of the chromophore. These results not only offer a strategy to expand SMLM imaging to a broad range of available biological models, but also present unique insights into the chemistry and functioning of a highly important class of fluorophores.

Efficient switching of mCherry fluorescence using chemical caging

PubMed Central

Cloin, Bas M. C.; Salas, Desiree; Gielen, Vincent; Folkers, Gert E.; Mikhaylova, Marina; Bergeler, Maike; Krajnik, Bartosz; Harvey, Jeremy; Hoogenraad, Casper C.; Van Meervelt, Luc; Dedecker, Peter; Kapitein, Lukas C.

2017-01-01

Fluorophores with dynamic or controllable fluorescence emission have become essential tools for advanced imaging, such as superresolution imaging. These applications have driven the continuing development of photoactivatable or photoconvertible labels, including genetically encoded fluorescent proteins. These new probes work well but require the introduction of new labels that may interfere with the proper functioning of existing constructs and therefore require extensive functional characterization. In this work we show that the widely used red fluorescent protein mCherry can be brought to a purely chemically induced blue-fluorescent state by incubation with β-mercaptoethanol (βME). The molecules can be recovered to the red fluorescent state by washing out the βME or through irradiation with violet light, with up to 80% total recovery. We show that this can be used to perform single-molecule localization microscopy (SMLM) on cells expressing mCherry, which renders this approach applicable to a very wide range of existing constructs. We performed a detailed investigation of the mechanism underlying these dynamics, using X-ray crystallography, NMR spectroscopy, and ab initio quantum-mechanical calculations. We find that the βME-induced fluorescence quenching of mCherry occurs both via the direct addition of βME to the chromophore and through βME-mediated reduction of the chromophore. These results not only offer a strategy to expand SMLM imaging to a broad range of available biological models, but also present unique insights into the chemistry and functioning of a highly important class of fluorophores. PMID:28630286

T-ray tomography.

PubMed

Mittleman, D M; Hunsche, S; Boivin, L; Nuss, M C

1997-06-15

We demonstrate tomographic T-ray imaging, using the timing information present in terahertz (THz) pulses in a reflection geometry. THz pulses are reflected from refractive-index discontinuities inside an object, and the time delays of these pulses are used to determine the positions of the discontinuities along the propagation direction. In this fashion a tomographic image can be constructed.

Computed tomographic findings of cerebral fat embolism following multiple bone fractures.

PubMed

Law, Huong Ling; Wong, Siong Lung; Tan, Suzet

2013-02-01

Fat embolism to the lungs and brain is an uncommon complication following fractures. Few reports with descriptions of computed tomographic (CT) findings of emboli to the brain or cerebral fat embolism are available. We report a case of cerebral fat embolism following multiple skeletal fractures and present its CT findings here.

Quantum-tomographic cryptography with a semiconductor single-photon source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaszlikowski, D.; Yang, L.J.; Yong, L.S.

2005-09-15

We analyze the security of so-called quantum-tomographic cryptography with the source producing entangled photons via an experimental scheme proposed by Fattal et al. [Phys. Rev. Lett. 92, 37903 (2004)]. We determine the range of the experimental parameters for which the protocol is secure against the most general incoherent attacks.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ceglio, N.M.; George, E.V.; Brooks, K.M.

The first successful demonstration of high resolution, tomographic imaging of a laboratory plasma using coded imaging techniques is reported. ZPCI has been used to image the x-ray emission from laser compressed DT filled microballoons. The zone plate camera viewed an x-ray spectral window extending from below 2 keV to above 6 keV. It exhibited a resolution approximately 8 ..mu..m, a magnification factor approximately 13, and subtended a radiation collection solid angle at the target approximately 10/sup -2/ sr. X-ray images using ZPCI were compared with those taken using a grazing incidence reflection x-ray microscope. The agreement was excellent. In addition,more » the zone plate camera produced tomographic images. The nominal tomographic resolution was approximately 75 ..mu..m. This allowed three dimensional viewing of target emission from a single shot in planar ''slices''. In addition to its tomographic capability, the great advantage of the coded imaging technique lies in its applicability to hard (greater than 10 keV) x-ray and charged particle imaging. Experiments involving coded imaging of the suprathermal x-ray and high energy alpha particle emission from laser compressed microballoon targets are discussed.« less

Tomography and the Herglotz-Wiechert inverse formulation

NASA Astrophysics Data System (ADS)

Nowack, Robert L.

1990-04-01

In this paper, linearized tomography and the Herglotz-Wiechert inverse formulation are compared. Tomographic inversions for 2-D or 3-D velocity structure use line integrals along rays and can be written in terms of Radon transforms. For radially concentric structures, Radon transforms are shown to reduce to Abel transforms. Therefore, for straight ray paths, the Abel transform of travel-time is a tomographic algorithm specialized to a one-dimensional radially concentric medium. The Herglotz-Wiechert formulation uses seismic travel-time data to invert for one-dimensional earth structure and is derived using exact ray trajectories by applying an Abel transform. This is of historical interest since it would imply that a specialized tomographic-like algorithm has been used in seismology since the early part of the century (see Herglotz, 1907; Wiechert, 1910). Numerical examples are performed comparing the Herglotz-Wiechert algorithm and linearized tomography along straight rays. Since the Herglotz-Wiechert algorithm is applicable under specific conditions, (the absence of low velocity zones) to non-straight ray paths, the association with tomography may prove to be useful in assessing the uniqueness of tomographic results generalized to curved ray geometries.

A detailed comparison of single-camera light-field PIV and tomographic PIV

NASA Astrophysics Data System (ADS)

Shi, Shengxian; Ding, Junfei; Atkinson, Callum; Soria, Julio; New, T. H.

2018-03-01

This paper conducts a comprehensive study between the single-camera light-field particle image velocimetry (LF-PIV) and the multi-camera tomographic particle image velocimetry (Tomo-PIV). Simulation studies were first performed using synthetic light-field and tomographic particle images, which extensively examine the difference between these two techniques by varying key parameters such as pixel to microlens ratio (PMR), light-field camera Tomo-camera pixel ratio (LTPR), particle seeding density and tomographic camera number. Simulation results indicate that the single LF-PIV can achieve accuracy consistent with that of multi-camera Tomo-PIV, but requires the use of overall greater number of pixels. Experimental studies were then conducted by simultaneously measuring low-speed jet flow with single-camera LF-PIV and four-camera Tomo-PIV systems. Experiments confirm that given a sufficiently high pixel resolution, a single-camera LF-PIV system can indeed deliver volumetric velocity field measurements for an equivalent field of view with a spatial resolution commensurate with those of multi-camera Tomo-PIV system, enabling accurate 3D measurements in applications where optical access is limited.

Efficient globally optimal segmentation of cells in fluorescence microscopy images using level sets and convex energy functionals.

PubMed

Bergeest, Jan-Philip; Rohr, Karl

2012-10-01

In high-throughput applications, accurate and efficient segmentation of cells in fluorescence microscopy images is of central importance for the quantification of protein expression and the understanding of cell function. We propose an approach for segmenting cell nuclei which is based on active contours using level sets and convex energy functionals. Compared to previous work, our approach determines the global solution. Thus, the approach does not suffer from local minima and the segmentation result does not depend on the initialization. We consider three different well-known energy functionals for active contour-based segmentation and introduce convex formulations of these functionals. We also suggest a numeric approach for efficiently computing the solution. The performance of our approach has been evaluated using fluorescence microscopy images from different experiments comprising different cell types. We have also performed a quantitative comparison with previous segmentation approaches. Copyright © 2012 Elsevier B.V. All rights reserved.

Comparison of fluorescence-based methods to determine nanoparticle uptake by phagocytes and non-phagocytic cells in vitro

PubMed Central

Claudia, Meindl; Kristin, Öhlinger; Jennifer, Ober; Eva, Roblegg; Eleonore, Fröhlich

2017-01-01

At many portals of entry the relative uptake by phagocytes and non-phagocytic cells has a prominent effect on availability and biological action of nanoparticles (NPs). Cellular uptake can be determined for fluorescence-labeled NPs. The present study compares three methods (plate reader, flow cytometry and image analysis) in order to investigate the influence of particle size and functionalization and medium content on cellular uptake of fluorescence–labeled polystyrene particles and to study the respective method’s suitability for uptake studies. For comparison between the techniques, ratios of macrophage to alveolar epithelial cell uptakes were used. Presence of serum protein in the exposure solution decreased uptake of carboxyl-functionalized and non-functionalized particles; there was no clear effect for the amine-functionalized particles. The 200 nm non- or carboxyl-functionalized NPs were taken up preferentially by phagocytes while for amine-functionalized particles preference was lowest. The presence of the serum slightly increased the preference for these particles. In conclusion, due to the possibility of calibration, plate reader measurements might present a better option than the other techniques to (semi)quantify differences between phagocytes and non-phagocytic cells for particles with different fluorescence. In order to obtain unbiased data the fluorescent labeling has to fulfill certain requirements. PMID:28065592

In Situ Live-Cell Nucleus Fluorescence Labeling with Bioinspired Fluorescent Probes.

PubMed

Ding, Pan; Wang, Houyu; Song, Bin; Ji, Xiaoyuan; Su, Yuanyuan; He, Yao

2017-08-01

Fluorescent imaging techniques for visualization of nuclear structure and function in live cells are fundamentally important for exploring major cellular events. The ideal cellular labeling method is capable of realizing label-free, in situ, real-time, and long-term nucleus labeling in live cells, which can fully obtain the nucleus-relative information and effectively alleviate negative effects of alien probes on cellular metabolism. However, current established fluorescent probes-based strategies (e.g., fluorescent proteins-, organic dyes-, fluorescent organic/inorganic nanoparticles-based imaging techniques) are unable to simultaneously realize label-free, in situ, long-term, and real-time nucleus labeling, resulting in inevitable difficulties in fully visualizing nuclear structure and function in live cells. To this end, we present a type of bioinspired fluorescent probes, which are highly efficacious for in situ and label-free tracking of nucleus in long-term and real-time manners. Typically, the bioinspired polydopamine (PDA) nanoparticles, served as fluorescent probes, can be readily synthesized in situ within live cell nucleus without any further modifications under physiological conditions (37 °C, pH ∼7.4). Compared with other conventional nuclear dyes (e.g., propidium iodide (PI), Hoechst), superior spectroscopic properties (e.g., quantum yield of ∼35.8% and high photostability) and low cytotoxicity of PDA-based probes enable long-term (e.g., 3 h) fluorescence tracking of nucleus. We also demonstrate the generality of this type of bioinspired fluorescent probes in different cell lines and complex biological samples.

Exchange of rotor components in functioning bacterial flagellar motor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fukuoka, Hajime; Inoue, Yuichi; Graduate School of Life Sciences, Tohoku University, Aoba-ku, Sendai 980-8577

2010-03-26

The bacterial flagellar motor is a rotary motor driven by the electrochemical potential of a coupling ion. The interaction between a rotor and stator units is thought to generate torque. The overall structure of flagellar motor has been thought to be static, however, it was recently proved that stators are exchanged in a rotating motor. Understanding the dynamics of rotor components in functioning motor is important for the clarifying of working mechanism of bacterial flagellar motor. In this study, we focused on the dynamics and the turnover of rotor components in a functioning flagellar motor. Expression systems for GFP-FliN, FliM-GFP,more » and GFP-FliG were constructed, and each GFP-fusion was functionally incorporated into the flagellar motor. To investigate whether the rotor components are exchanged in a rotating motor, we performed fluorescence recovery after photobleaching experiments using total internal reflection fluorescence microscopy. After photobleaching, in a tethered cell producing GFP-FliN or FliM-GFP, the recovery of fluorescence at the rotational center was observed. However, in a cell producing GFP-FliG, no recovery of fluorescence was observed. The transition phase of fluorescence intensity after full or partially photobleaching allowed the turnover of FliN subunits to be calculated as 0.0007 s{sup -1}, meaning that FliN would be exchanged in tens of minutes. These novel findings indicate that a bacterial flagellar motor is not a static structure even in functioning state. This is the first report for the exchange of rotor components in a functioning bacterial flagellar motor.« less

New Frontiers in NanoBiotechnology: Monitoring the Protein Function With Single Protein Resolution

DTIC Science & Technology

2005-03-29

Protein (GFP) is a spontaneously fluorescent polypeptide of 27 kD from the jellyfish Aequorea victoria that absorbs UV-blue light and emits in the...will have vast applications in science. Relationship between structure and optical properties in Green Fluorescent Proteins : A quantum mechanical study...RESEARCH AND DEVELOPMENT Invited talks Folding, stability and fluorescence efficiency of the Green and Red Fluorescent Proteins Saverio Alberti Lab.

Hierarchical multimodal tomographic x-ray imaging at a superbend

NASA Astrophysics Data System (ADS)

Stampanoni, M.; Marone, F.; Mikuljan, G.; Jefimovs, K.; Trtik, P.; Vila-Comamala, J.; David, C.; Abela, R.

2008-08-01

Over the last decade, synchrotron-based X-ray tomographic microscopy has established itself as a fundamental tool for non-invasive, quantitative investigations of a broad variety of samples, with application ranging from space research and materials science to biology and medicine. Thanks to the brilliance of modern third generation sources, voxel sizes in the micrometer range are routinely achieved by the major X-ray microtomography devices around the world, while the isotropic 100 nm barrier is reached and trespassed only by few instruments. The beamline for TOmographic Microscopy and Coherent rAdiology experiments (TOMCAT) of the Swiss Light Source at the Paul Scherrer Institut, operates a multimodal endstation which offers tomographic capabilities in the micrometer range in absorption contrast - of course - as well as phase contrast imaging. Recently, the beamline has been equipped with a full field, hard X-rays microscope with a theoretical pixel size down to 30 nm and a field of view of 50 microns. The nanoscope performs well at X-ray energies between 8 and 12 keV, selected from the white beam of a 2.9 T superbend by a [Ru/C]100 fixed exit multilayer monochromator. In this work we illustrate the experimental setup dedicated to the nanoscope, in particular the ad-hoc designed X-ray optics needed to produce a homogeneous, square illumination of the sample imaging plane as well as the magnifying zone plate. Tomographic reconstructions at 60 nm voxel size will be shown and discussed.

Field-portable lensfree tomographic microscope.

PubMed

Isikman, Serhan O; Bishara, Waheb; Sikora, Uzair; Yaglidere, Oguzhan; Yeah, John; Ozcan, Aydogan

2011-07-07

We present a field-portable lensfree tomographic microscope, which can achieve sectional imaging of a large volume (∼20 mm(3)) on a chip with an axial resolution of <7 μm. In this compact tomographic imaging platform (weighing only ∼110 grams), 24 light-emitting diodes (LEDs) that are each butt-coupled to a fibre-optic waveguide are controlled through a cost-effective micro-processor to sequentially illuminate the sample from different angles to record lensfree holograms of the sample that is placed on the top of a digital sensor array. In order to generate pixel super-resolved (SR) lensfree holograms and hence digitally improve the achievable lateral resolution, multiple sub-pixel shifted holograms are recorded at each illumination angle by electromagnetically actuating the fibre-optic waveguides using compact coils and magnets. These SR projection holograms obtained over an angular range of ±50° are rapidly reconstructed to yield projection images of the sample, which can then be back-projected to compute tomograms of the objects on the sensor-chip. The performance of this compact and light-weight lensfree tomographic microscope is validated by imaging micro-beads of different dimensions as well as a Hymenolepis nana egg, which is an infectious parasitic flatworm. Achieving a decent three-dimensional spatial resolution, this field-portable on-chip optical tomographic microscope might provide a useful toolset for telemedicine and high-throughput imaging applications in resource-poor settings. This journal is © The Royal Society of Chemistry 2011

DIRECT OBSERVATION OF SOLAR CORONAL MAGNETIC FIELDS BY VECTOR TOMOGRAPHY OF THE CORONAL EMISSION LINE POLARIZATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kramar, M.; Lin, H.; Tomczyk, S., E-mail: kramar@cua.edu, E-mail: lin@ifa.hawaii.edu, E-mail: tomczyk@ucar.edu

We present the first direct “observation” of the global-scale, 3D coronal magnetic fields of Carrington Rotation (CR) Cycle 2112 using vector tomographic inversion techniques. The vector tomographic inversion uses measurements of the Fe xiii 10747 Å Hanle effect polarization signals by the Coronal Multichannel Polarimeter (CoMP) and 3D coronal density and temperature derived from scalar tomographic inversion of Solar Terrestrial Relations Observatory (STEREO)/Extreme Ultraviolet Imager (EUVI) coronal emission lines (CELs) intensity images as inputs to derive a coronal magnetic field model that best reproduces the observed polarization signals. While independent verifications of the vector tomography results cannot be performed, wemore » compared the tomography inverted coronal magnetic fields with those constructed by magnetohydrodynamic (MHD) simulations based on observed photospheric magnetic fields of CR 2112 and 2113. We found that the MHD model for CR 2112 is qualitatively consistent with the tomography inverted result for most of the reconstruction domain except for several regions. Particularly, for one of the most noticeable regions, we found that the MHD simulation for CR 2113 predicted a model that more closely resembles the vector tomography inverted magnetic fields. In another case, our tomographic reconstruction predicted an open magnetic field at a region where a coronal hole can be seen directly from a STEREO-B/EUVI image. We discuss the utilities and limitations of the tomographic inversion technique, and present ideas for future developments.« less

Relative arrival-time upper-mantle tomography and the elusive background mean

NASA Astrophysics Data System (ADS)

Bastow, Ian D.

2012-08-01

The interpretation of seismic tomographic images of upper-mantle seismic wave speed structure is often a matter of considerable debate because the observations can usually be explained by a range of hypotheses, including variable temperature, composition, anisotropy, and the presence of partial melt. An additional problem, often overlooked in tomographic studies using relative as opposed to absolute arrival-times, is the issue of the resulting velocity model's zero mean. In shield areas, for example, relative arrival-time analysis strips off a background mean velocity structure that is markedly fast compared to the global average. Conversely, in active areas, the background mean is often markedly slow compared to the global average. Appreciation of this issue is vital when interpreting seismic tomographic images: 'high' and 'low' velocity anomalies should not necessarily be interpreted, respectively, as 'fast' and 'slow' compared to 'normal mantle'. This issue has been discussed in the seismological literature in detail over the years, yet subsequent tomography studies have still fallen into the trap of mis-interpreting their velocity models. I highlight here some recent examples of this and provide a simple strategy to address the problem using constraints from a recent global tomographic model, and insights from catalogues of absolute traveltime anomalies. Consultation of such absolute measures of seismic wave speed should be routine during regional tomographic studies, if only for the benefit of the broader Earth Science community, who readily follow the red = hot and slow, blue = cold and fast rule of thumb when interpreting the images for themselves.

Fluorescence and afterglow of Ca2Sn2Al2O9:Mn2+

NASA Astrophysics Data System (ADS)

Takemoto, Minoru; Iseki, Takahiro

2018-03-01

By using a polymerized complex method, we synthesized manganese (Mn)-doped Ca2Sn2Al2O9, which exhibits yellow fluorescence and afterglow at room temperature when excited by UV radiation. The material emits a broad, featureless fluorescence band centered at 564 nm, which we attribute to the presence of Mn2+ ions. The afterglow decay is well fit by a power-law function, rather than an exponential function. In addition, thermoluminescence analyses demonstrate that two different types of electron traps form in this material. Based on experimental results, we conclude that the fluorescence and afterglow both result from thermally assisted tunneling, in which trapped electrons are thermally excited to higher-level traps and subsequently tunnel to recombination centers.

Transplantation and tracking of human-induced pluripotent stem cells in a pig model of myocardial infarction: assessment of cell survival, engraftment, and distribution by hybrid single photon emission computed tomography/computed tomography of sodium iodide symporter transgene expression.

PubMed

Templin, Christian; Zweigerdt, Robert; Schwanke, Kristin; Olmer, Ruth; Ghadri, Jelena-Rima; Emmert, Maximilian Y; Müller, Ennio; Küest, Silke M; Cohrs, Susan; Schibli, Roger; Kronen, Peter; Hilbe, Monika; Reinisch, Andreas; Strunk, Dirk; Haverich, Axel; Hoerstrup, Simon; Lüscher, Thomas F; Kaufmann, Philipp A; Landmesser, Ulf; Martin, Ulrich

2012-07-24

Evaluation of novel cellular therapies in large-animal models and patients is currently hampered by the lack of imaging approaches that allow for long-term monitoring of viable transplanted cells. In this study, sodium iodide symporter (NIS) transgene imaging was evaluated as an approach to follow in vivo survival, engraftment, and distribution of human-induced pluripotent stem cell (hiPSC) derivatives in a pig model of myocardial infarction. Transgenic hiPSC lines stably expressing a fluorescent reporter and NIS (NIS(pos)-hiPSCs) were established. Iodide uptake, efflux, and viability of NIS(pos)-hiPSCs were assessed in vitro. Ten (±2) days after induction of myocardial infarction by transient occlusion of the left anterior descending artery, catheter-based intramyocardial injection of NIS(pos)-hiPSCs guided by 3-dimensional NOGA mapping was performed. Dual-isotope single photon emission computed tomographic/computed tomographic imaging was applied with the use of (123)I to follow donor cell survival and distribution and with the use of (99m)TC-tetrofosmin for perfusion imaging. In vitro, iodide uptake in NIS(pos)-hiPSCs was increased 100-fold above that of nontransgenic controls. In vivo, viable NIS(pos)-hiPSCs could be visualized for up to 15 weeks. Immunohistochemistry demonstrated that hiPSC-derived endothelial cells contributed to vascularization. Up to 12 to 15 weeks after transplantation, no teratomas were detected. This study describes for the first time the feasibility of repeated long-term in vivo imaging of viability and tissue distribution of cellular grafts in large animals. Moreover, this is the first report demonstrating vascular differentiation and long-term engraftment of hiPSCs in a large-animal model of myocardial infarction. NIS(pos)-hiPSCs represent a valuable tool to monitor and improve current cellular treatment strategies in clinically relevant animal models.

Development of Functional Fluorescent Molecular Probes for the Detection of Biological Substances

PubMed Central

Suzuki, Yoshio; Yokoyama, Kenji

2015-01-01

This review is confined to sensors that use fluorescence to transmit biochemical information. Fluorescence is, by far, the most frequently exploited phenomenon for chemical sensors and biosensors. Parameters that define the application of such sensors include intensity, decay time, anisotropy, quenching efficiency, and luminescence energy transfer. To achieve selective (bio)molecular recognition based on these fluorescence phenomena, various fluorescent elements such as small organic molecules, enzymes, antibodies, and oligonucleotides have been designed and synthesized over the past decades. This review describes the immense variety of fluorescent probes that have been designed for the recognitions of ions, small and large molecules, and their biological applications in terms of intracellular fluorescent imaging techniques. PMID:26095660

The enhanced cyan fluorescent protein: a sensitive pH sensor for fluorescence lifetime imaging.

PubMed

Poëa-Guyon, Sandrine; Pasquier, Hélène; Mérola, Fabienne; Morel, Nicolas; Erard, Marie

2013-05-01

pH is an important parameter that affects many functions of live cells, from protein structure or function to several crucial steps of their metabolism. Genetically encoded pH sensors based on pH-sensitive fluorescent proteins have been developed and used to monitor the pH of intracellular compartments. The quantitative analysis of pH variations can be performed either by ratiometric or fluorescence lifetime detection. However, most available genetically encoded pH sensors are based on green and yellow fluorescent proteins and are not compatible with multicolor approaches. Taking advantage of the strong pH sensitivity of enhanced cyan fluorescent protein (ECFP), we demonstrate here its suitability as a sensitive pH sensor using fluorescence lifetime imaging. The intracellular ECFP lifetime undergoes large changes (32 %) in the pH 5 to pH 7 range, which allows accurate pH measurements to better than 0.2 pH units. By fusion of ECFP with the granular chromogranin A, we successfully measured the pH in secretory granules of PC12 cells, and we performed a kinetic analysis of intragranular pH variations in living cells exposed to ammonium chloride.

Correlative Microscopy of Vitreous Sections Provides Insights into BAR-Domain Organization In Situ.

PubMed

Bharat, Tanmay A M; Hoffmann, Patrick C; Kukulski, Wanda

2018-04-10

Electron microscopy imaging of macromolecular complexes in their native cellular context is limited by the inherent difficulty to acquire high-resolution tomographic data from thick cells and to specifically identify elusive structures within crowded cellular environments. Here, we combined cryo-fluorescence microscopy with electron cryo-tomography of vitreous sections into a coherent correlative microscopy workflow, ideal for detection and structural analysis of elusive protein assemblies in situ. We used this workflow to address an open question on BAR-domain coating of yeast plasma membrane compartments known as eisosomes. BAR domains can sense or induce membrane curvature, and form scaffold-like membrane coats in vitro. Our results demonstrate that in cells, the BAR protein Pil1 localizes to eisosomes of varying membrane curvature. Sub-tomogram analysis revealed a dense protein coat on curved eisosomes, which was not present on shallow eisosomes, indicating that while BAR domains can assemble at shallow membranes in vivo, scaffold formation is tightly coupled to curvature generation. Copyright © 2018 MRC Laboratory of Molecular Biology. Published by Elsevier Ltd.. All rights reserved.

Recruitment dynamics of ESCRT-III and Vps4 to endosomes and implications for reverse membrane budding

PubMed Central

Bykov, Yury S; Sprenger, Simon; Pakdel, Mehrshad; Vogel, Georg F; Jih, Gloria; Skillern, Wesley; Behrouzi, Reza; Babst, Markus; Schmidt, Oliver; Hess, Michael W; Briggs, John AG

2017-01-01

The ESCRT machinery mediates reverse membrane scission. By quantitative fluorescence lattice light-sheet microscopy, we have shown that ESCRT-III subunits polymerize rapidly on yeast endosomes, together with the recruitment of at least two Vps4 hexamers. During their 3–45 s lifetimes, the ESCRT-III assemblies accumulated 75–200 Snf7 and 15–50 Vps24 molecules. Productive budding events required at least two additional Vps4 hexamers. Membrane budding was associated with continuous, stochastic exchange of Vps4 and ESCRT-III components, rather than steady growth of fixed assemblies, and depended on Vps4 ATPase activity. An all-or-none step led to final release of ESCRT-III and Vps4. Tomographic electron microscopy demonstrated that acute disruption of Vps4 recruitment stalled membrane budding. We propose a model in which multiple Vps4 hexamers (four or more) draw together several ESCRT-III filaments. This process induces cargo crowding and inward membrane buckling, followed by constriction of the nascent bud neck and ultimately ILV generation by vesicle fission. PMID:29019322

A laboratory system for element specific hyperspectral X-ray imaging.

PubMed

Jacques, Simon D M; Egan, Christopher K; Wilson, Matthew D; Veale, Matthew C; Seller, Paul; Cernik, Robert J

2013-02-21

X-ray tomography is a ubiquitous tool used, for example, in medical diagnosis, explosives detection or to check structural integrity of complex engineered components. Conventional tomographic images are formed by measuring many transmitted X-rays and later mathematically reconstructing the object, however the structural and chemical information carried by scattered X-rays of different wavelengths is not utilised in any way. We show how a very simple; laboratory-based; high energy X-ray system can capture these scattered X-rays to deliver 3D images with structural or chemical information in each voxel. This type of imaging can be used to separate and identify chemical species in bulk objects with no special sample preparation. We demonstrate the capability of hyperspectral imaging by examining an electronic device where we can clearly distinguish the atomic composition of the circuit board components in both fluorescence and transmission geometries. We are not only able to obtain attenuation contrast but also to image chemical variations in the object, potentially opening up a very wide range of applications from security to medical diagnostics.

Green fluorescent protein nanopolygons as monodisperse supramolecular assemblies of functional proteins with defined valency

PubMed Central

Kim, Young Eun; Kim, Yu-na; Kim, Jung A.; Kim, Ho Min; Jung, Yongwon

2015-01-01

Supramolecular protein assemblies offer novel nanoscale architectures with molecular precision and unparalleled functional diversity. A key challenge, however, is to create precise nano-assemblies of functional proteins with both defined structures and a controlled number of protein-building blocks. Here we report a series of supramolecular green fluorescent protein oligomers that are assembled in precise polygonal geometries and prepared in a monodisperse population. Green fluorescent protein is engineered to be self-assembled in cells into oligomeric assemblies that are natively separated in a single-protein resolution by surface charge manipulation, affording monodisperse protein (nano)polygons from dimer to decamer. Several functional proteins are multivalently displayed on the oligomers with controlled orientations. Spatial arrangements of protein oligomers and displayed functional proteins are directly visualized by a transmission electron microscope. By employing our functional protein assemblies, we provide experimental insight into multivalent protein–protein interactions and tools to manipulate receptor clustering on live cell surfaces. PMID:25972078

Next-Generation Theranostic Agents Based on Polyelectrolyte Microcapsules Encoded with Semiconductor Nanocrystals: Development and Functional Characterization

NASA Astrophysics Data System (ADS)

Nifontova, Galina; Zvaigzne, Maria; Baryshnikova, Maria; Korostylev, Evgeny; Ramos-Gomes, Fernanda; Alves, Frauke; Nabiev, Igor; Sukhanova, Alyona

2018-01-01

Fabrication of polyelectrolyte microcapsules and their use as carriers of drugs, fluorescent labels, and metal nanoparticles is a promising approach to designing theranostic agents. Semiconductor quantum dots (QDs) are characterized by extremely high brightness and photostability that make them attractive fluorescent labels for visualization of intracellular penetration and delivery of such microcapsules. Here, we describe an approach to design, fabricate, and characterize physico-chemical and functional properties of polyelectrolyte microcapsules encoded with water-solubilized and stabilized with three-functional polyethylene glycol derivatives core/shell QDs. Developed microcapsules were characterized by dynamic light scattering, electrophoretic mobility, scanning electronic microscopy, and fluorescence and confocal microscopy approaches, providing exact data on their size distribution, surface charge, morphological, and optical characteristics. The fluorescence lifetimes of the QD-encoded microcapsules were also measured, and their dependence on time after preparation of the microcapsules was evaluated. The optimal content of QDs used for encoding procedure providing the optimal fluorescence properties of the encoded microcapsules was determined. Finally, the intracellular microcapsule uptake by murine macrophages was demonstrated, thus confirming the possibility of efficient use of developed system for live cell imaging and visualization of microcapsule transportation and delivery within the living cells.

Near-infrared fluorescence cholangiography with indocyanine green for biliary atresia. Real-time imaging during the Kasai procedure: a pilot study.

PubMed

Hirayama, Yutaka; Iinuma, Yasushi; Yokoyama, Naoyuki; Otani, Tetsuya; Masui, Daisuke; Komatsuzaki, Naoko; Higashidate, Naruki; Tsuruhisa, Shiori; Iida, Hisataka; Nakaya, Kengo; Naito, Shinichi; Nitta, Koju; Yagi, Minoru

2015-12-01

Hepatoportoenterostomy (HPE) with the Kasai procedure is the treatment of choice for biliary atresia (BA) as the initial surgery. However, the appropriate level of dissection level of the fibrous cone (FC) of the porta hepatis (PH) is frequently unclear, and the procedure sometimes results in unsuccessful outcomes. Recently, indocyanine green near-infrared fluorescence imaging (ICG-FCG) has been developed as a form of real-time cholangiography. We applied this technique in five patients with BA to visualize the biliary flow at the PH intraoperatively. ICG was injected intravenously the day before surgery as the liver function test, and the liver was observed with a near-infrared camera system during the operation while the patient's feces was also observed. In all patients, the whole liver fluoresced diffusely with ICG-containing stagnant bile, whereas no extrahepatic structures fluoresced. The findings of the ICG fluorescence pattern of the PH after dissection of the FC were classified into three types: spotty fluorescence, one patient; diffuse weak fluorescence, three patients; and diffuse strong fluorescence, one patient. In all five patients, the feces evacuated after HPE showed distinct fluorescent spots, although that obtained before surgery showed no fluorescence. One patient with diffuse strong fluorescence who did not achieve JF underwent living related liver transplantation six months after the initial HPE procedure. Four patients, including three cases involving diffuse weak fluorescence and one case involving spotty fluorescence showed weak fluorescence compared to that of the surrounding liver surface. We were able to detect the presence of bile excretion at the time of HPE intraoperatively and successfully evaluated the extent of bile excretion using this new technique. Furthermore, the ICG-FCG findings may provide information leading to a new classification and potentially function as an indicator predicting the clinical outcomes after HPE.

Interdisciplinary Study of Egyptian Mummies from the Pushkin State Museum of Fine Arts Collection at the National Research Centre ``Kurchatov Institute''

NASA Astrophysics Data System (ADS)

Yatsishina, E. B.; Kovalchuk, M. V.; Loshak, M. D.; Vasilyev, S. V.; Vasilieva, O. A.; Dyuzheva, O. P.; Pojidaev, V. M.; Ushakov, V. L.

2018-05-01

Nine ancient Egyptian mummies (dated preliminarily to the period from the 1st mill. BCE to the first centuries CE) from the collection of the State Pushkin Museum of Fine Arts have been studied at the National Research Centre "Kurchatov Institute" (NRC KI) on the base of the complex of NBICS technologies. Tomographic scanning is performed using a magneto-resonance tomograph (3 T) and a hybrid positron emission tomography/computed tomography (PET-CT) scanner. Three-dimensional reconstructions of mummies and their anthropological measurements are carried out. Some medical conclusions are drawn based on the tomographic data. In addition, the embalming composition and tissue of one of the mummies are preliminarily analyzed.

System for plotting subsoil structure and method therefor

NASA Technical Reports Server (NTRS)

Narasimhan, K. Y.; Nathan, R.; Parthasarathy, S. P. (Inventor)

1980-01-01

Data for use in producing a tomograph of subsoil structure between boreholes is derived by pacing spaced geophones in one borehole, on the Earth surface if desired, and by producing a sequence of shots at spaced apart locations in the other borehole. The signals, detected by each of the geophones from the various shots, are processed either on a time of arrival basis, or on the basis of signal amplitude, to provide information of the characteristics of a large number of incremental areas between the boreholes. Such information is useable to produce a tomograph of the subsoil structure between the boreholes. By processing signals of relatively high frequencies, e.g., up to 100 Hz, and by closely spacing the geophones, a high resolution tomograph can be produced.

Robust statistical reconstruction for charged particle tomography

DOEpatents

Schultz, Larry Joe; Klimenko, Alexei Vasilievich; Fraser, Andrew Mcleod; Morris, Christopher; Orum, John Christopher; Borozdin, Konstantin N; Sossong, Michael James; Hengartner, Nicolas W

2013-10-08

Systems and methods for charged particle detection including statistical reconstruction of object volume scattering density profiles from charged particle tomographic data to determine the probability distribution of charged particle scattering using a statistical multiple scattering model and determine a substantially maximum likelihood estimate of object volume scattering density using expectation maximization (ML/EM) algorithm to reconstruct the object volume scattering density. The presence of and/or type of object occupying the volume of interest can be identified from the reconstructed volume scattering density profile. The charged particle tomographic data can be cosmic ray muon tomographic data from a muon tracker for scanning packages, containers, vehicles or cargo. The method can be implemented using a computer program which is executable on a computer.

Data-processing strategies for nano-tomography with elemental specification

NASA Astrophysics Data System (ADS)

Liu, Yijin; Cats, Korneel H.; Nelson Weker, Johanna; Andrews, Joy C.; Weckhuysen, Bert M.; Pianetta, Piero

2013-10-01

Combining the energy tunability provided by synchrotron X-ray sources with transmission X-ray microscopy, the morphology of materials can be resolved in 3D at spatial resolution down to 30 nm with elemental/chemical specification. In order to study the energy dependence of the absorption coefficient over the investigated volume, the tomographic reconstruction and image registration (before and/or after the tomographic reconstruction) are critical. We show in this paper the comparison of two different data processing strategies and conclude that the signal to noise ratio (S/N) in the final result can be improved via performing tomographic reconstruction prior to the evaluation of energy dependence. Our result echoes the dose fractionation theorem, and is particularly helpful when the element of interest has low concentration.

Enhancement of fluorescence intensity by silicon particles and its size effect.

PubMed

Saitow, Ken-ichi; Suemori, Hidemi; Tamamitsu, Hironori

2014-02-04

Fluorescence-intensity enhancement of dye molecules was investigated using silicon submicron particles as a function of the particle size. Silicon particles with a size of 500 nm gave an enhancement factor up to 180. Measurement of scattering spectra revealed that the localized electric field at the particle enhances the fluorescence intensity.

Investigating structure-property relationships of biomineralized calcium phosphate compounds as fluorescent quenching-recovery platform

NASA Astrophysics Data System (ADS)

Wang, Liuzheng; He, Xiang; Zhang, Wei; Liu, Yong; Banks, Craig E.; Zhang, Ying

2018-02-01

The structure-property relationship between biomineralized calcium phosphate compounds upon a fluorescent quenching-recovery platform and their distinct crystalline structure and surficial functional groups are investigated. A fluorescence-based sensing platform is shown to be viable for the sensing of 8-hydroxy-2-deoxy-guanosine in simulated systems.

In vivo labeling of cortical astrocytes with sulforhodamine 101 (SR101).

PubMed

Nimmerjahn, Axel; Helmchen, Fritjof

2012-03-01

Fluorescent markers that stain particular cell types in the intact brain are essential tools for fluorescence microscopy because they enable studies of structure and function of cells identified in this way. Although cell type-specific fluorescence staining can be achieved through promoter-driven expression of fluorescent proteins, this genetic approach is generally labor- and cost-intensive. Alternative viral approaches for targeted fluorophore expression are relatively invasive. For astrocytes, there is a simple alternative. This protocol describes an easy and robust method for rapid (within minutes) and high-contrast staining of astrocytes in defined regions of the intact rodent cortex using the synthetic, water-soluble but non-fixable red fluorescent dye sulforhodamine 101 (SR101). Selective staining is achieved through local uptake and gap junction-mediated spread of SR101 following its topical application or injection into tissue. Applications, technical pitfalls, and limitations of the SR101-staining technique are discussed. Given its simplicity and reliability, SR101 staining is a valuable tool for the study of astrocyte function in the intact brain and for in vivo fluorescence microscopy in general.

Multimodal optoacoustic and multiphoton fluorescence microscopy

NASA Astrophysics Data System (ADS)

Sela, Gali; Razansky, Daniel; Shoham, Shy

2013-03-01

Multiphoton microscopy is a powerful imaging modality that enables structural and functional imaging with cellular and sub-cellular resolution, deep within biological tissues. Yet, its main contrast mechanism relies on extrinsically administered fluorescent indicators. Here we developed a system for simultaneous multimodal optoacoustic and multiphoton fluorescence 3D imaging, which attains both absorption and fluorescence-based contrast by integrating an ultrasonic transducer into a two-photon laser scanning microscope. The system is readily shown to enable acquisition of multimodal microscopic images of fluorescently labeled targets and cell cultures as well as intrinsic absorption-based images of pigmented biological tissue. During initial experiments, it was further observed that that detected optoacoustically-induced response contains low frequency signal variations, presumably due to cavitation-mediated signal generation by the high repetition rate (80MHz) near IR femtosecond laser. The multimodal system may provide complementary structural and functional information to the fluorescently labeled tissue, by superimposing optoacoustic images of intrinsic tissue chromophores, such as melanin deposits, pigmentation, and hemoglobin or other extrinsic particle or dye-based markers highly absorptive in the NIR spectrum.

Fluorescent nanodiamonds as highly stable biomarker for endotoxin verification

NASA Astrophysics Data System (ADS)

Bergmann, Thorsten; Burg, Jan Michael; Lilholt, Maria; Maeder, Ulf; Beer, Sebastian; Salzig, Denise; Ebrahimi, Mehrdad; Czermak, Peter; Fiebich, Martin

2012-03-01

Fluorescent nanodiamonds (ND) provide advantageous properties as a fluorescent biomarker for in vitro and in vivo studies. The maximum fluorescence occurs around 700 nm, they do not show photobleaching or blinking and seem to be nontoxic. After a pretreatment with strong acid fluorescent ND can be functionalized and coupled to endotoxin. Endotoxin is a decay product of bacteria and causes strong immune reactions. Therefore endotoxin has to be removed for most applications. An effective removal procedure is membrane filtration. The endotoxin, coupled to fluorescent ND can be visualized by using confocal microscopy which allows the investigation of the separation mechanisms of the filtration process within the membranes.

A Novel method for the preparation of fluorescent C60 poly(amino acid) composites and their biological imaging.

PubMed

Xu, Dazhuang; Liu, Meiying; Huang, Qiang; Chen, Junyu; Huang, Hongye; Deng, Fengjie; Tian, Jianwen; Wen, Yuanqing; Zhang, Xiaoyong; Wei, Yen

2018-04-15

Recently, fullerene (C 60 ) and its derivatives have been widely explored for many applications owing to their enriched physical and chemical properties. Specifically, the synthesis and biomedical applications of fluorescent C 60 have been extensively investigated previously. However, the preparation of polymer-functionalized fluorescent C 60 has not been reported thus far. In this study, water-dispersible fluorescent C 60 polymer composites were successfully synthesized through the combination of the thiol-ene click reaction and subsequent ring-opening polymerization. First, 2-aminoethanethiol was introduced on the surface of C 60 by the thiol-ene click reaction. The surface of amino group-functionalized C 60 (C 60 -NH 2 ) was further modified with poly(amino acid)s via ring-open polymerization of GluEG N-carboxyanhydrides (NCAs). The morphology, functional groups, optical properties and biocompatibility were examined by a number of characterization equipment and assays in detail. We demonstrated that the resultant fluorescent C 60 poly(amino acid) (C 60 -GluEG) composites have a small size (about 5 nm), high water dispersibility, intense fluorescence and high photostability. Cell viability results implied that the C 60 -GluEG composites possess low cytotoxicity. Moreover, these C 60 -GluEG composites can easily penetrate into live cells, indicating their great potential for biological imaging applications. Copyright © 2018 Elsevier Inc. All rights reserved.

"Turn-on" fluorescence detection of lead ions based on accelerated leaching of gold nanoparticles on the surface of graphene.

PubMed

Fu, Xiuli; Lou, Tingting; Chen, Zhaopeng; Lin, Meng; Feng, Weiwei; Chen, Lingxin

2012-02-01

A novel platform for effective "turn-on" fluorescence sensing of lead ions (Pb(2+)) in aqueous solution was developed based on gold nanoparticle (AuNP)-functionalized graphene. The AuNP-functionalized graphene exhibited minimal background fluorescence because of the extraordinarily high quenching ability of AuNPs. Interestingly, the AuNP-functionalized graphene underwent fluorescence restoration as well as significant enhancement upon adding Pb(2+), which was attributed to the fact that Pb(2+) could accelerate the leaching rate of the AuNPs on graphene surfaces in the presence of both thiosulfate (S(2)O(3)(2-)) and 2-mercaptoethanol (2-ME). Consequently, this could be utilized as the basis for selective detection of Pb(2+). With the optimum conditions chosen, the relative fluorescence intensity showed good linearity versus logarithm concentration of Pb(2+) in the range of 50-1000 nM (R = 0.9982), and a detection limit of 10 nM. High selectivity over common coexistent metal ions was also demonstrated. The practical application had been carried out for determination of Pb(2+) in tap water and mineral water samples. The Pb(2+)-specific "turn-on" fluorescence sensor, based on Pb(2+) accelerated leaching of AuNPs on the surface of graphene, provided new opportunities for highly sensitive and selective Pb(2+) detection in aqueous media.

Preparation of fluorescent tocopherols for use in protein binding and localization with the alpha-tocopherol transfer protein.

PubMed

Nava, Phillip; Cecchini, Matt; Chirico, Sara; Gordon, Heather; Morley, Samantha; Manor, Danny; Atkinson, Jeffrey

2006-06-01

Sixteen fluorescent analogues of the lipid-soluble antioxidant vitamin alpha-tocopherol were prepared incorporating fluorophores at the terminus of omega-functionalized 2-n-alkyl-substituted chromanols (1a-d and 4a-d) that match the methylation pattern of alpha-tocopherol, the most biologically active form of vitamin E. The fluorophores used include 9-anthroyloxy (AO), 7-nitrobenz-2-oxa-1,3-diazole (NBD), N-methyl anthranilamide (NMA), and dansyl (DAN). The compounds were designed to function as fluorescent reporter ligands for protein-binding and lipid transfer assays. The fluorophores were chosen to maximize the fluorescence changes observed upon moving from an aqueous environment (low fluorescence intensity) to an hydrophobic environment such as a protein's binding site (high fluorescence intensity). Compounds 9d (anthroyloxy) and 10d (nitrobenzoxadiazole), having a C9-carbon chain between the chromanol and the fluorophore, were shown to bind specifically and reversibly to recombinant human tocopherol transfer protein (alpha-TTP) with dissociation constants of approximately 280 and 60 nM, respectively, as compared to 25 nM for the natural ligand 2R,4'R,8'R-alpha-tocopherol. Thus, compounds have been prepared that allow the investigation of the rate of alpha-TTP-mediated inter-membrane transfer of alpha-tocopherol and to investigate the mechanism of alpha-TTP function at membranes of different composition.

Correlative cellular ptychography with functionalized nanoparticles at the Fe L-edge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gallagher-Jones, Marcus; Dias, Carlos Sato Baraldi; Pryor, Alan

Precise localization of nanoparticles within a cell is crucial to the understanding of cell-particle interactions and has broad applications in nanomedicine. Here in this paper, we report a proof-of-principle experiment for imaging individual functionalized nanoparticles within a mammalian cell by correlative microscopy. Using a chemically-fixed HeLa cell labeled with fluorescent core-shell nanoparticles as a model system, we implemented a graphene-oxide layer as a substrate to significantly reduce background scattering. We identified cellular features of interest by fluorescence microscopy, followed by scanning transmission X-ray tomography to localize the particles in 3D, and ptychographic coherent diffractive imaging of the fine features inmore » the region at high resolution. By tuning the X-ray energy to the Fe L-edge, we demonstrated sensitive detection of nanoparticles composed of a 22 nm magnetic Fe 3O 4 core encased by a 25-nm-thick fluorescent silica (SiO 2) shell. These fluorescent core-shell nanoparticles act as landmarks and offer clarity in a cellular context. Our correlative microscopy results confirmed a subset of particles to be fully internalized, and high-contrast ptychographic images showed two oxidation states of individual nanoparticles with a resolution of ~16.5 nm. The ability to precisely localize individual fluorescent nanoparticles within mammalian cells will expand our understanding of the structure/function relationships for functionalized nanoparticles.« less

Correlative cellular ptychography with functionalized nanoparticles at the Fe L-edge

DOE PAGES

Gallagher-Jones, Marcus; Dias, Carlos Sato Baraldi; Pryor, Alan; ...

2017-07-06

Precise localization of nanoparticles within a cell is crucial to the understanding of cell-particle interactions and has broad applications in nanomedicine. Here in this paper, we report a proof-of-principle experiment for imaging individual functionalized nanoparticles within a mammalian cell by correlative microscopy. Using a chemically-fixed HeLa cell labeled with fluorescent core-shell nanoparticles as a model system, we implemented a graphene-oxide layer as a substrate to significantly reduce background scattering. We identified cellular features of interest by fluorescence microscopy, followed by scanning transmission X-ray tomography to localize the particles in 3D, and ptychographic coherent diffractive imaging of the fine features inmore » the region at high resolution. By tuning the X-ray energy to the Fe L-edge, we demonstrated sensitive detection of nanoparticles composed of a 22 nm magnetic Fe 3O 4 core encased by a 25-nm-thick fluorescent silica (SiO 2) shell. These fluorescent core-shell nanoparticles act as landmarks and offer clarity in a cellular context. Our correlative microscopy results confirmed a subset of particles to be fully internalized, and high-contrast ptychographic images showed two oxidation states of individual nanoparticles with a resolution of ~16.5 nm. The ability to precisely localize individual fluorescent nanoparticles within mammalian cells will expand our understanding of the structure/function relationships for functionalized nanoparticles.« less

It is all about location: how to pinpoint microorganisms and their functions in multispecies biofilms.

PubMed

Costa, Angela M; Mergulhão, Filipe J; Briandet, Romain; Azevedo, Nuno F

2017-09-01

Multispecies biofilms represent the dominant mode of life for the vast majority of microorganisms. Bacterial spatial localization in such biostructures governs ecological interactions between different populations and triggers the overall community functions. Here, we discuss the pros and cons of fluorescence-based techniques used to decipher bacterial species patterns in biofilms at single cell level, including fluorescence in situ hybridization and the use of genetically modified bacteria that express fluorescent proteins, reporting the significant improvements of those techniques. The development of tools for spatial and temporal study of multispecies biofilms will allow live imaging and spatial localization of cells in naturally occurring biofilms coupled with metabolic information, increasing insight of microbial community and the relation between its structure and functions.

Colorimetric and Fluorescent Biosensors Based on Directed Assembly of Nanomaterials with Functional DNA

NASA Astrophysics Data System (ADS)

Liu, Juewen; Lu, Yi

This chapter reviews recent progress in the interface between functional nucleic acids and nanoscale science and technology, and its analytical applications. In particular, the use of metallic nanoparticles as the color reporting groups for the action (binding, catalysis, or both) of aptamers, DNAzymes, and aptazymes is described in detail. Because metallic nanoparticles possess high extinction coefficients and distance-dependent optical properties, they allow highly sensitive detections with minimal consumption of materials. The combination of quantum dots (QDs) with functional nucleic acids as fluorescent sensors is also described. The chapter starts with the design of colorimetric and fluorescent sensors responsive to single analytes, followed by sensors responsive to multiple analytes with controllable cooperativity and multiplex detection using both colorimetric and fluorescent signals in one pot, and ends by transferring solution-based detections into litmus paper type of tests, making them generally applicable and usable for a wide range of on-site and real-time analytical applications such as household tests, environmental monitoring, and clinical diagnostics.

New hexa-bodipy functionalized dendrimeric cyclotriphosphazene conjugates as highly selective and sensitive fluorescent chemosensor for Co2+ ions.

PubMed

Şenkuytu, Elif; Tanrıverdi Eçik, Esra

2018-06-05

In the study, the new hexa-bodipy functionalized dendrimeric cyclotriphosphazene conjugates (HBCP 1 and 2) have been successfully synthesized and characterized by using general spectroscopic techniques such as 1 H, 13 C and 31 P NMR spectroscopies. The photophysical and metal sensing properties in THF solutions of dendrimeric cyclotriphosphazene conjugates (HBCP 1 and 2) were investigated by UV-Vis and fluorescence spectroscopies in dilute tetrahydrofuran solutions. These dendrimers showed strong absorption bands 501 and 641nm at low concentration with high molar extinction coefficients. In addition, the stoichiometry of the complex between the conjugate (HBCP 2) and Co 2+ ions were determined by a Job's plot obtained from fluorescence titrations. The metal sensing data showed that the hexa-bodipy functionalized dendrimeric cyclotriphosphazene conjugate (HBCP 2) is a candidate for fluorescent chemosensor for Co 2+ ions due to showing high selectivity with a low limit of detection. Copyright © 2018 Elsevier B.V. All rights reserved.

CIE colorimetric system fails to calculate the chroma of a Nd:YAG crystal under the fluorescent illuminant F7

NASA Astrophysics Data System (ADS)

Liu, Yan; Chen, Qinghan; Bu, Xianhui; Feng, Pingyun

2002-06-01

The rare earth element neodymium doped yttrium aluminum garnet (Nd:YAG) is a laser crystal widely used for producing laser in the infrared range. Neodymium causes many characteristic absorption peaks in the transmittance spectrum of the Nd:YAG crystal in the visible range. The crystal appears pink under daylight and incandescent light, and colorless under fluorescent light. The colorimetric calculation results of chroma under the CIE standard fluorescent illuminant F7 do not agree with the color appearance under fluorescent light. The calculated chroma values should be near zero to agree with a colorless appearance, but it is actually 11.79 in the CIELAB color space. This failure of the colorimetric calculation is caused by the color matching functions of the CIE colorimetric observers. The color matching functions do not agree with the spectral sensitivity curves of the human eye, especially the x(λ) function does not matches the spectral sensitivity curve of the long wavelength cone photoreceptors.

Crustal and Upper Mantle Investigations Using Receiver Functions and Tomographic Inversion in the Southern Puna Plateau Region of the Central Andes

NASA Astrophysics Data System (ADS)

Heit, B.; Yuan, X.; Bianchi, M.; Jakovlev, A.; Kumar, P.; Kay, S. M.; Sandvol, E. A.; Alonso, R.; Coira, B.; Comte, D.; Brown, L. D.; Kind, R.

2011-12-01

We present here the results obtained using the data form our passive seismic array in the southern Puna plateau between 25°S to 28°S latitude in Argentina and Chile. In first instance we have been able to calculate P and S receiver functions in order to investigate the Moho thickness and other seismic discontinuities in the study area. The RF data shows that the northern Puna plateau has a thicker crust and that the Moho topography is more irregular along strike. The seismic structure and thickness of the continental crust and the lithospheric mantle beneath the southern Puna plateau reveals that the LAB is deeper to the north of the array suggesting lithospheric removal towards the south. Later we performed a joint inversion of teleseismic and regional tomographic data in order to study the distribution of velocity anomalies that could help us to better understand the evolution of the Andean elevated plateau and the role of lithosphere-asthenosphere interactions in this region. Low velocities are observed in correlation with young volcanic centers (e.g. Ojos del Salado, Cerro Blanco, Galan) and agree very well with the position of crustal lineaments in the region. This is suggesting a close relationship between magmatism and lithospheric structures at crustal scale coniciding with the presence of hot asthenospheric material at the base of the crust probably induced by lithospheric foundering.

Enhanced Rayleigh waves tomography of Mexico using ambient noise cross-correlations (C1) and correlations of coda of correlations (C3)

NASA Astrophysics Data System (ADS)

Spica, Z. J.; Perton, M.; Calo, M.; Cordoba-Montiel, F.; Legrand, D.; Iglesias, A.

2015-12-01

Standard application of the seismic ambient noise tomography considers the existence of synchronous records at stations for green's functions retrieval. More recent theoretical and experimental observations showed the possibility to apply correlation of coda of noise correlation (C3) to obtain green's functions between stations of asynchronous seismic networks making possible to dramatically increase databases for imagining the Earth's interior. However, this possibility has not been fully exploited yet, and right now the data C3 are not included into tomographic inversions to refine seismic structures. Here we show for the first time how to incorporate the data of C1 and C3 to calculate dispersion maps of Rayleigh waves in the range period of 10-120s, and how the merging of these datasets improves the resolution of the structures imaged. Tomographic images are obtained for an area covering Mexico, the Gulf of Mexico and the southern U.S. We show dispersion maps calculated using both data of C1 and the complete dataset (C1+C3). The latter provide new details of the seismic structure of the region allowing a better understanding of their role on the geodynamics of the study area. The resolving power obtained in our study is several times higher than in previous studies based on ambient noise. This demonstrates the new possibilities for imaging the Earth's crust and upper mantle using this enlarged database.

Hyperspectral Computed Tomographic Imaging Spectroscopy of Vascular Oxygen Gradients in the Rabbit Retina In Vivo

PubMed Central

Kashani, Amir H.; Kirkman, Erlinda; Martin, Gabriel; Humayun, Mark S.

2011-01-01

Diagnosis of retinal vascular diseases depends on ophthalmoscopic findings that most often occur after severe visual loss (as in vein occlusions) or chronic changes that are irreversible (as in diabetic retinopathy). Despite recent advances, diagnostic imaging currently reveals very little about the vascular function and local oxygen delivery. One potentially useful measure of vascular function is measurement of hemoglobin oxygen content. In this paper, we demonstrate a novel method of accurately, rapidly and easily measuring oxygen saturation within retinal vessels using in vivo imaging spectroscopy. This method uses a commercially available fundus camera coupled to two-dimensional diffracting optics that scatter the incident light onto a focal plane array in a calibrated pattern. Computed tomographic algorithms are used to reconstruct the diffracted spectral patterns into wavelength components of the original image. In this paper the spectral components of oxy- and deoxyhemoglobin are analyzed from the vessels within the image. Up to 76 spectral measurements can be made in only a few milliseconds and used to quantify the oxygen saturation within the retinal vessels over a 10–15 degree field. The method described here can acquire 10-fold more spectral data in much less time than conventional oximetry systems (while utilizing the commonly accepted fundus camera platform). Application of this method to animal models of retinal vascular disease and clinical subjects will provide useful and novel information about retinal vascular disease and physiology. PMID:21931729

KiDS+GAMA: cosmology constraints from a joint analysis of cosmic shear, galaxy-galaxy lensing, and angular clustering

NASA Astrophysics Data System (ADS)

van Uitert, Edo; Joachimi, Benjamin; Joudaki, Shahab; Amon, Alexandra; Heymans, Catherine; Köhlinger, Fabian; Asgari, Marika; Blake, Chris; Choi, Ami; Erben, Thomas; Farrow, Daniel J.; Harnois-Déraps, Joachim; Hildebrandt, Hendrik; Hoekstra, Henk; Kitching, Thomas D.; Klaes, Dominik; Kuijken, Konrad; Merten, Julian; Miller, Lance; Nakajima, Reiko; Schneider, Peter; Valentijn, Edwin; Viola, Massimo

2018-06-01

We present cosmological parameter constraints from a joint analysis of three cosmological probes: the tomographic cosmic shear signal in ˜450 deg2 of data from the Kilo Degree Survey (KiDS), the galaxy-matter cross-correlation signal of galaxies from the Galaxies And Mass Assembly (GAMA) survey determined with KiDS weak lensing, and the angular correlation function of the same GAMA galaxies. We use fast power spectrum estimators that are based on simple integrals over the real-space correlation functions, and show that they are practically unbiased over relevant angular frequency ranges. We test our full pipeline on numerical simulations that are tailored to KiDS and retrieve the input cosmology. By fitting different combinations of power spectra, we demonstrate that the three probes are internally consistent. For all probes combined, we obtain S_8≡ σ _8 √{Ω _m/0.3}=0.800_{-0.027}^{+0.029}, consistent with Planck and the fiducial KiDS-450 cosmic shear correlation function results. Marginalizing over wide priors on the mean of the tomographic redshift distributions yields consistent results for S8 with an increase of 28 {per cent} in the error. The combination of probes results in a 26 per cent reduction in uncertainties of S8 over using the cosmic shear power spectra alone. The main gain from these additional probes comes through their constraining power on nuisance parameters, such as the galaxy intrinsic alignment amplitude or potential shifts in the redshift distributions, which are up to a factor of 2 better constrained compared to using cosmic shear alone, demonstrating the value of large-scale structure probe combination.

Imaging Lithospheric-scale Structure Beneath Northern Altiplano in Southern Peru and Northern Bolivia

NASA Astrophysics Data System (ADS)

Kumar, A.; Wagner, L. S.; Beck, S. L.; Zandt, G.; Long, M. D.

2014-12-01

The northern Altiplano plateau of southern Peru and northern Bolivia is one of the highest topographic features on the Earth, flanked by Western and Eastern Cordillera along its margin. It has strongly influenced the local and far field lithospheric deformation since the early Miocene (Masek et al., 1994). Previous studies have emphasized the importance of both the crust and upper mantle in the evolution of Altiplano plateau (McQuarrie et al., 2005). Early tomographic and receiver function studies, south of 16° S, show significant variations in the crust and upper mantle properties in both perpendicular and along strike direction of the Altiplano plateau (Dorbath et. al., 1993; Myers et al., 1998; Beck and Zandt, 2002). In order to investigate the nature of subsurface lithospheric structure below the northern Altiplano, between 15-18° S, we have determined three-dimensional seismic tomography models for Vp and Vs using P and S-wave travel time data from two recently deployed local seismic networks of CAUGHT and PULSE. We also used data from 8 stations from the PERUSE network (PERU Subduction Experiment). Our preliminary tomographic models show a complex variation in the upper mantle velocity structure with depth, northwest and southeast of lake Titicaca. We see the following trend, at ~85 km depth, northwest of lake Titicaca: low Vp and Vs beneath the Western Cordillera, high Vs beneath the Altiplano and low Vp and Vs beneath the Eastern Cordillera. This low velocity anomaly, beneath Eastern Cordillera, seems to coincide with Kimsachata, a Holocene volcano in southern Peru. At depth greater than ~85 km: we find high velocity anomaly beneath the Western Cordillera and low Vs beneath the Altiplano. This high velocity anomaly, beneath Western Cordillera, coincides with the well-located Wadati-Benioff zone seismicity and perhaps represents the subducting Nazca slab. On the southeast of lake Titicaca, in northern Bolivia, we see a consistently high velocity anomaly that continues deeper as a westward dipping high velocity structure in the upper mantle. Our further in depth modelling and tomographic constraints on Vp/Vs would allow us to better resolve the lithospheric features that we see in our preliminary tomographic models and their possible correlations with the evolution of northern Altiplano plateau.

Certain tricyclic and pentacyclic-hetero nitrogen rhodol dyes

DOEpatents

Haugland, Richard P.; Whitaker, James E.

1993-01-01

Novel fluorescent dyes based on the rhodol structure are provided. The new reagents contain functional groups capable of forming a stable fluorescent product with functional groups typically found in biomolecules or polymers including amines, phenols, thiols, acids, aldehydes and ketones. Reactive groups in the rhodol dyes include activated esters, isothiocyanates, amines, hydrazines, halides, acids, azides, maleimides, aldehydes, alcohols, acrylamides and haloacetamides. The products are detected by their absorbance or fluorescence properties. The spectral properties of the fluorescent dyes are sufficiently similar in wavelengths and intensity to fluorescein or rhodamine derivatives as to permit use of the same equipment. The dyes, however, show less spectral sensitivity to pH in the physiological range than does fluorescein, have higher solubility in non-polar solvents and have improved photostability and quantum yields.

Synthesis and bio-applications of targeted magnetic-fluorescent composite nanoparticles

NASA Astrophysics Data System (ADS)

Xia, Hui; Tong, Ruijie; Song, Yanling; Xiong, Fang; Li, Jiman; Wang, Shichao; Fu, Huihui; Wen, Jirui; Li, Dongze; Zeng, Ye; Zhao, Zhiwei; Wu, Jiang

2017-04-01

Magnetic-fluorescent nanoparticles have a tremendous potential in biology. As the benefits of these materials gained recognition, increasing attention has been given to the conjugation of magnetic-fluorescent nanoparticles with targeting ligands. The magnetic and fluorescent properties of nanoparticles offer several functionalities, including imaging, separation, and visualization, while the presence of a targeting ligand allows for selective cell and tissue targeting. In this review, methods for the synthesis of targeted magnetic-fluorescent nanoparticles are explored, and recent applications of these nanocomposites to the detection and separation of biomolecules, fluorescent and magnetic resonance imaging, and cancer diagnosis and treatment will be summarized. As these materials are further optimized, targeted magnetic-fluorescent nanoparticles hold great promise for the diagnosis and treatment of some diseases.

ReAsH/FlAsH labeling and image analysis of tetracysteine sensor proteins in cells.

PubMed

Irtegun, Sevgi; Ramdzan, Yasmin M; Mulhern, Terrence D; Hatters, Danny M

2011-08-31

Fluorescent proteins and dyes are essential tools for the study of protein trafficking, localization and function in cells. While fluorescent proteins such as green fluorescence protein (GFP) have been extensively used as fusion partners to proteins to track the properties of a protein of interest, recent developments with smaller tags enable new functionalities of proteins to be examined in cells such as conformational change and protein-association. One small tag system involves a tetracysteine motif (CCXXCC) genetically inserted into a target protein, which binds to biarsenical dyes, ReAsH (red fluorescent) and FlAsH (green fluorescent), with high specificity even in live cells. The TC/biarsenical dye system offers far less steric constraints to the host protein than fluorescent proteins which has enabled several new approaches to measure conformational change and protein-protein interactions. We recently developed a novel application of TC tags as sensors of oligomerization in cells expressing mutant huntingtin, which when mutated aggregates in neurons in Huntington disease. Huntingtin was tagged with two fluorescent dyes, one a fluorescent protein to track protein location, and the second a TC tag which only binds biarsenical dyes in monomers. Hence, changes in colocalization between protein and biarsenical dye reactivity enabled submicroscopic oligomer content to be spatially mapped within cells. Here, we describe how to label TC-tagged proteins fused to a fluorescent protein (Cherry, GFP or CFP) with FlAsH or ReAsH in live mammalian cells and how to quantify the two color fluorescence (Cherry/FlAsH, CFP/FlAsH or GFP/ReAsH combinations).

Fluorescence imaging of tryptophan and collagen cross-links to evaluate wound closure ex vivo

NASA Astrophysics Data System (ADS)

Wang, Ying; Ortega-Martinez, Antonio; Farinelli, Bill; Anderson, R. R.; Franco, Walfre

2016-02-01

Wound size is a key parameter in monitoring healing. Current methods to measure wound size are often subjective, time-consuming and marginally invasive. Recently, we developed a non-invasive, non-contact, fast and simple but robust fluorescence imaging (u-FEI) method to monitor the healing of skin wounds. This method exploits the fluorescence of native molecules to tissue as functional and structural markers. The objective of the present study is to demonstrate the feasibility of using variations in the fluorescence intensity of tryptophan and cross-links of collagen to evaluate proliferation of keratinocyte cells and quantitate size of wound during healing, respectively. Circular dermal wounds were created in ex vivo human skin and cultured in different media. Two serial fluorescence images of tryptophan and collagen cross-links were acquired every two days. Histology and immunohistology were used to validate correlation between fluorescence and epithelialization. Images of collagen cross-links show fluorescence of the exposed dermis and, hence, are a measure of wound area. Images of tryptophan show higher fluorescence intensity of proliferating keratinocytes forming new epithelium, as compared to surrounding keratinocytes not involved in epithelialization. These images are complementary since collagen cross-links report on structure while tryptophan reports on function. HE and immunohistology show that tryptophan fluorescence correlates with newly formed epidermis. We have established a fluorescence imaging method for studying epithelialization processes during wound healing in a skin organ culture model, our approach has the potential to provide a non-invasive, non-contact, quick, objective and direct method for quantitative measurements in wound healing in vivo.

Detection of Naja atra Cardiotoxin Using Adenosine-Based Molecular Beacon.

PubMed

Shi, Yi-Jun; Chen, Ying-Jung; Hu, Wan-Ping; Chang, Long-Sen

2017-01-07

This study presents an adenosine (A)-based molecular beacon (MB) for selective detection of Naja atra cardiotoxin (CTX) that functions by utilizing the competitive binding between CTX and the poly(A) stem of MB to coralyne. The 5'- and 3'-end of MB were labeled with a reporter fluorophore and a non-fluorescent quencher, respectively. Coralyne induced formation of the stem-loop MB structure through A₂-coralyne-A₂ coordination, causing fluorescence signal turn-off due to fluorescence resonance energy transfer between the fluorophore and quencher. CTX3 could bind to coralyne. Moreover, CTX3 alone induced the folding of MB structure and quenching of MB fluorescence. Unlike that of snake venom α-neurotoxins, the fluorescence signal of coralyne-MB complexes produced a bell-shaped concentration-dependent curve in the presence of CTX3 and CTX isotoxins; a turn-on fluorescence signal was noted when CTX concentration was ≤80 nM, while a turn-off fluorescence signal was noted with a further increase in toxin concentrations. The fluorescence signal of coralyne-MB complexes yielded a bell-shaped curve in response to varying concentrations of N. atra crude venom but not those of Bungarus multicinctus and Protobothrops mucrosquamatus venoms. Moreover, N. nigricollis venom also functioned as N. atra venom to yield a bell-shaped concentration-dependent curve of MB fluorescence signal, again supporting that the hairpin-shaped MB could detect crude venoms containing CTXs. Taken together, our data validate that a platform composed of coralyne-induced stem-loop MB structure selectively detects CTXs.

Macroscopic monolayer of plasmon coupled gold nanoparticles on mirror for fluorescence enhancement

NASA Astrophysics Data System (ADS)

Kaydashev, V. E.; Zolotukhin, P.; Belanova, A.; Anokhin, A. S.; Zharinov, V. S.; Kaidashev, E. M.

2018-04-01

We study an ability of a large quasi-homogeneous monolayer of Au plasmon coupled nanoparticles separated from continuous Au film by polymer spacer to enhance a fluorescence of adsorbed molecular species. A fluorescence response of Methylene Blue molecules is studied as a function of polymer film thickness. A change of plasmonic properties of a system, its ability to enhance a fluorescence and the possible heating of a structure upon light absorption are discussed.

A multiresolution inversion for imaging the ionosphere

NASA Astrophysics Data System (ADS)

Yin, Ping; Zheng, Ya-Nan; Mitchell, Cathryn N.; Li, Bo

2017-06-01

Ionospheric tomography has been widely employed in imaging the large-scale ionospheric structures at both quiet and storm times. However, the tomographic algorithms to date have not been very effective in imaging of medium- and small-scale ionospheric structures due to limitations of uneven ground-based data distributions and the algorithm itself. Further, the effect of the density and quantity of Global Navigation Satellite Systems data that could help improve the tomographic results for the certain algorithm remains unclear in much of the literature. In this paper, a new multipass tomographic algorithm is proposed to conduct the inversion using intensive ground GPS observation data and is demonstrated over the U.S. West Coast during the period of 16-18 March 2015 which includes an ionospheric storm period. The characteristics of the multipass inversion algorithm are analyzed by comparing tomographic results with independent ionosonde data and Center for Orbit Determination in Europe total electron content estimates. Then, several ground data sets with different data distributions are grouped from the same data source in order to investigate the impact of the density of ground stations on ionospheric tomography results. Finally, it is concluded that the multipass inversion approach offers an improvement. The ground data density can affect tomographic results but only offers improvements up to a density of around one receiver every 150 to 200 km. When only GPS satellites are tracked there is no clear advantage in increasing the density of receivers beyond this level, although this may change if multiple constellations are monitored from each receiving station in the future.

Computed tomographic contrast tenography of the digital flexor tendon sheath of the equine hindlimb.

PubMed

Agass, Rachel; Dixon, Jonathon; Fraser, Barny

2018-05-01

Pre-surgical investigation of digital flexor tendon sheath pathology remains challenging with current standard imaging techniques. The aim of this prospective, anatomical, pilot study was to describe the anatomy of the equine hind limb digital flexor tendon sheath using a combination of computed tomography (CT) and computed tomographic contrast tenography in clinically normal cadaver limbs. Ten pairs of hind limbs with no external abnormalities were examined from the level of the tarsometatarsal joint distally. Limbs initially underwent non-contrast CT examination using 120 kVp, 300 mAs, and 1.5 mm slice thickness. Sixty millilitres of ioversol iodinated contrast media and saline (final concentration 100 mg/ml) were injected using a basilar sesamoidean approach. The computed tomographic contrast tenography examination was then repeated, before dissection of the specimens to compare gross and imaging findings. The combined CT and computed tomographic contrast tenography examinations provided excellent anatomical detail of intra-thecal structures. The borders of the superficial and deep digital flexor tendons, and the manica flexoria were consistently identifiable in all limbs. Detailed anatomy including that of the mesotenons, two of which are previously undescribed, and the plantar annular ligament were also consistently identifiable. Dissection of all 10 pairs of limbs revealed there to be no pathology, in accordance with the imaging findings. In conclusion, the combination of CT and computed tomographic contrast tenography may be useful adjunctive diagnostic techniques to define digital flexor tendon sheath pathology prior to surgical exploration in horses. © 2017 American College of Veterinary Radiology.

Tomographic phase analysis to detect the site of accessory conduction pathway in Wolff-Parkinson-White syndrome

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakajima, K.; Bunko, H.; Tada, A.

1984-01-01

Phase analysis has been applied to Wolff-Parkinson-White syndrome (WPW) to detect the site of accessory conduction pathway (ACP); however, there was a limitation to estimate the precise location of ACP by planar phase analysis. In this study, the authors applied phase analysis to gated blood pool tomography. Twelve patients with WPW who underwent epicardial mapping and surgical division of ACP were studied by both of gated emission computed tomography (GECT) and routine gated blood pool study (GBPS). The GBPS was performed with Tc-99m red blood cells in multiple projections; modified left anterior oblique, right anterior oblique and/or left lateral views.more » In GECT, short axial, horizontal and vertical long axial blood pool images were reconstructed. Phase analysis was performed using fundamental frequency of the Fourier transform in both GECT and GBPS images, and abnormal initial contractions on both the planar and tomographic phase analysis were compared with the location of surgically confirmed ACPs. In planar phase analysis, abnormal initial phase was identified in 7 out of 12 (58%) patients, while in tomographic phase analysis, the localization of ACP was predicted in 11 out of 12 (92%) patients. Tomographic phase analysis is superior to planar phase images in 8 out of 12 patients to estimate the location of ACP. Phase analysis by GECT can avoid overlap of blood pool in cardiac chambers and has advantage to identify the propagation of phase three-dimensionally. Tomographic phase analysis is a good adjunctive method for patients with WPW to estimate the site of ACP.« less

Iterative reconstruction of volumetric particle distribution

NASA Astrophysics Data System (ADS)

Wieneke, Bernhard

2013-02-01

For tracking the motion of illuminated particles in space and time several volumetric flow measurement techniques are available like 3D-particle tracking velocimetry (3D-PTV) recording images from typically three to four viewing directions. For higher seeding densities and the same experimental setup, tomographic PIV (Tomo-PIV) reconstructs voxel intensities using an iterative tomographic reconstruction algorithm (e.g. multiplicative algebraic reconstruction technique, MART) followed by cross-correlation of sub-volumes computing instantaneous 3D flow fields on a regular grid. A novel hybrid algorithm is proposed here that similar to MART iteratively reconstructs 3D-particle locations by comparing the recorded images with the projections calculated from the particle distribution in the volume. But like 3D-PTV, particles are represented by 3D-positions instead of voxel-based intensity blobs as in MART. Detailed knowledge of the optical transfer function and the particle image shape is mandatory, which may differ for different positions in the volume and for each camera. Using synthetic data it is shown that this method is capable of reconstructing densely seeded flows up to about 0.05 ppp with similar accuracy as Tomo-PIV. Finally the method is validated with experimental data.

Design and initial performance of PlanTIS: a high-resolution positron emission tomograph for plants

NASA Astrophysics Data System (ADS)

Beer, S.; Streun, M.; Hombach, T.; Buehler, J.; Jahnke, S.; Khodaverdi, M.; Larue, H.; Minwuyelet, S.; Parl, C.; Roeb, G.; Schurr, U.; Ziemons, K.

2010-02-01

Positron emitters such as 11C, 13N and 18F and their labelled compounds are widely used in clinical diagnosis and animal studies, but can also be used to study metabolic and physiological functions in plants dynamically and in vivo. A very particular tracer molecule is 11CO2 since it can be applied to a leaf as a gas. We have developed a Plant Tomographic Imaging System (PlanTIS), a high-resolution PET scanner for plant studies. Detectors, front-end electronics and data acquisition architecture of the scanner are based on the ClearPET™ system. The detectors consist of LSO and LuYAP crystals in phoswich configuration which are coupled to position-sensitive photomultiplier tubes. Signals are continuously sampled by free running ADCs, and data are stored in a list mode format. The detectors are arranged in a horizontal plane to allow the plants to be measured in the natural upright position. Two groups of four detector modules stand face-to-face and rotate around the field-of-view. This special system geometry requires dedicated image reconstruction and normalization procedures. We present the initial performance of the detector system and first phantom and plant measurements.

Cerebral blood-flow tomography: xenon-133 compared with isopropyl-amphetamine-iodine-123: concise communication

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lassen, N.A.; Henriksen, L.; Holm, S.

1983-01-01

Tomographic maps of local cerebral blood flow (CBF) were obtained with xenon-133 and with isopropyl-amphetamine-iodine-123 (IMP) in 11 subjects: one normal, two tumor cases, and eight cerebrovascular cases. A highly sensitive four-face, rapidly rotating, single-photon emission tomograph was used. The Xe-133 flow maps are essentially based on the average Xe-133 concentration over the initial 2 min during and after an inhalation of the inert gas lasting 1 min. These maps agreed very well with the early IMP maps obtained over the initial 10 min following an i.v. bolus injection. The subsequent IMP tomograms showed a slight decrease in contrast amountingmore » to appr. five percentage points in the CBF ratio between diseased and contralateral areas. It is concluded that Xe-133 is more practical: low cost, available on a 7-day basis, easily repeatable, quantifiable without the need for arterial sampling, and with low radiation exposure to patient and personnel. On the other hand, IMP gives an image of slightly higher resolution. It also introduces a new class of iodinated brain-seeking compounds allowing, perhaps, imaging of other functions more important than mere blood flow.« less

Design and initial performance of PlanTIS: a high-resolution positron emission tomograph for plants.

PubMed

Beer, S; Streun, M; Hombach, T; Buehler, J; Jahnke, S; Khodaverdi, M; Larue, H; Minwuyelet, S; Parl, C; Roeb, G; Schurr, U; Ziemons, K

2010-02-07

Positron emitters such as (11)C, (13)N and (18)F and their labelled compounds are widely used in clinical diagnosis and animal studies, but can also be used to study metabolic and physiological functions in plants dynamically and in vivo. A very particular tracer molecule is (11)CO(2) since it can be applied to a leaf as a gas. We have developed a Plant Tomographic Imaging System (PlanTIS), a high-resolution PET scanner for plant studies. Detectors, front-end electronics and data acquisition architecture of the scanner are based on the ClearPET system. The detectors consist of LSO and LuYAP crystals in phoswich configuration which are coupled to position-sensitive photomultiplier tubes. Signals are continuously sampled by free running ADCs, and data are stored in a list mode format. The detectors are arranged in a horizontal plane to allow the plants to be measured in the natural upright position. Two groups of four detector modules stand face-to-face and rotate around the field-of-view. This special system geometry requires dedicated image reconstruction and normalization procedures. We present the initial performance of the detector system and first phantom and plant measurements.

3D acoustic atmospheric tomography

NASA Astrophysics Data System (ADS)

Rogers, Kevin; Finn, Anthony

2014-10-01

This paper presents a method for tomographically reconstructing spatially varying 3D atmospheric temperature profiles and wind velocity fields based. Measurements of the acoustic signature measured onboard a small Unmanned Aerial Vehicle (UAV) are compared to ground-based observations of the same signals. The frequency-shifted signal variations are then used to estimate the acoustic propagation delay between the UAV and the ground microphones, which are also affected by atmospheric temperature and wind speed vectors along each sound ray path. The wind and temperature profiles are modelled as the weighted sum of Radial Basis Functions (RBFs), which also allow local meteorological measurements made at the UAV and ground receivers to supplement any acoustic observations. Tomography is used to provide a full 3D reconstruction/visualisation of the observed atmosphere. The technique offers observational mobility under direct user control and the capacity to monitor hazardous atmospheric environments, otherwise not justifiable on the basis of cost or risk. This paper summarises the tomographic technique and reports on the results of simulations and initial field trials. The technique has practical applications for atmospheric research, sound propagation studies, boundary layer meteorology, air pollution measurements, analysis of wind shear, and wind farm surveys.

Exceptionally Preserved Cambrian Trilobite Digestive System Revealed in 3D by Synchrotron-Radiation X-Ray Tomographic Microscopy

PubMed Central

Eriksson, Mats E.; Terfelt, Fredrik

2012-01-01

The Cambrian ‘Orsten’ fauna comprises exceptionally preserved and phosphatised microscopic arthropods. The external morphology of these fossils is well known, but their internal soft-tissue anatomy has remained virtually unknown. Here, we report the first non-biomineralised tissues from a juvenile polymerid trilobite, represented by digestive structures, glands, and connective strands harboured in a hypostome from the Swedish ‘Orsten’ fauna. Synchrotron-radiation X-ray tomographic microscopy enabled three-dimensional internal recordings at sub-micrometre resolution. The specimen provides the first unambiguous evidence for a J-shaped anterior gut and the presence of a crop with a constricted alimentary tract in the Trilobita. Moreover, the gut is Y-shaped in cross section, probably due to a collapsed lumen of that shape, another feature which has not previously been observed in trilobites. The combination of anatomical features suggests that the trilobite hypostome is functionally analogous to the labrum of euarthropods and that it was a sophisticated element closely integrated with the digestive system. This study also briefly addresses the preservational bias of the ‘Orsten’ fauna, particularly the near-absence of polymerid trilobites, and the taphonomy of the soft-tissue-harbouring hypostome. PMID:22558180

Exceptionally preserved Cambrian trilobite digestive system revealed in 3D by synchrotron-radiation X-ray tomographic microscopy.

PubMed

Eriksson, Mats E; Terfelt, Fredrik

2012-01-01

The Cambrian 'Orsten' fauna comprises exceptionally preserved and phosphatised microscopic arthropods. The external morphology of these fossils is well known, but their internal soft-tissue anatomy has remained virtually unknown. Here, we report the first non-biomineralised tissues from a juvenile polymerid trilobite, represented by digestive structures, glands, and connective strands harboured in a hypostome from the Swedish 'Orsten' fauna. Synchrotron-radiation X-ray tomographic microscopy enabled three-dimensional internal recordings at sub-micrometre resolution. The specimen provides the first unambiguous evidence for a J-shaped anterior gut and the presence of a crop with a constricted alimentary tract in the Trilobita. Moreover, the gut is Y-shaped in cross section, probably due to a collapsed lumen of that shape, another feature which has not previously been observed in trilobites. The combination of anatomical features suggests that the trilobite hypostome is functionally analogous to the labrum of euarthropods and that it was a sophisticated element closely integrated with the digestive system. This study also briefly addresses the preservational bias of the 'Orsten' fauna, particularly the near-absence of polymerid trilobites, and the taphonomy of the soft-tissue-harbouring hypostome.

Tomographic Structural Changes of Retinal Layers after Internal Limiting Membrane Peeling for Macular Hole Surgery.

PubMed

Faria, Mun Yueh; Ferreira, Nuno P; Cristóvao, Diana M; Mano, Sofia; Sousa, David Cordeiro; Monteiro-Grillo, Manuel

2018-01-01

To highlight tomographic structural changes of retinal layers after internal limiting membrane (ILM) peeling in macular hole surgery. Nonrandomized prospective, interventional study in 38 eyes (34 patients) subjected to pars plana vitrectomy and ILM peeling for idiopathic macular hole. Retinal layers were assessed in nasal and temporal regions before and 6 months after surgery using spectral domain optical coherence tomography. Total retinal thickness increased in the nasal region and decreased in the temporal region. The retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), and inner plexiform layer (IPL) showed thinning on both nasal and temporal sides of the fovea. The thickness of the outer plexiform layer (OPL) increased. The outer nuclear layer (ONL) and outer retinal layers (ORL) increased in thickness after surgery in both nasal and temporal regions. ILM peeling is associated with important alterations in the inner retinal layer architecture, with thinning of the RNFL-GCL-IPL complex and thickening of OPL, ONL, and ORL. These structural alterations can help explain functional outcome and could give indications regarding the extent of ILM peeling, even though peeling seems important for higher rate of hole closure. © 2017 S. Karger AG, Basel.

Brainstem auditory-evoked potentials as an objective tool for evaluating hearing dysfunction in traumatic brain injury.

PubMed

Lew, Henry L; Lee, Eun Ha; Miyoshi, Yasushi; Chang, Douglas G; Date, Elaine S; Jerger, James F

2004-03-01

Because of the violent nature of traumatic brain injury, traumatic brain injury patients are susceptible to various types of trauma involving the auditory system. We report a case of a 55-yr-old man who presented with communication problems after traumatic brain injury. Initial results from behavioral audiometry and Weber/Rinne tests were not reliable because of poor cooperation. He was transferred to our service for inpatient rehabilitation, where review of the initial head computed tomographic scan showed only left temporal bone fracture. Brainstem auditory-evoked potential was then performed to evaluate his hearing function. The results showed bilateral absence of auditory-evoked responses, which strongly suggested bilateral deafness. This finding led to a follow-up computed tomographic scan, with focus on bilateral temporal bones. A subtle transverse fracture of the right temporal bone was then detected, in addition to the left temporal bone fracture previously identified. Like children with hearing impairment, traumatic brain injury patients may not be able to verbalize their auditory deficits in a timely manner. If hearing loss is suspected in a patient who is unable to participate in traditional behavioral audiometric testing, brainstem auditory-evoked potential may be an option for evaluating hearing dysfunction.

Chlorophyll fluorescence lifetime imaging provides new insight into the chlorosis induced by plant virus infection.

PubMed

Lei, Rong; Jiang, Hongshan; Hu, Fan; Yan, Jin; Zhu, Shuifang

2017-02-01

Leaf chlorosis induced by plant virus infection has a short fluorescence lifetime, which reflects damaged photosynthetic complexes and degraded chloroplasts. Plant viruses often induce chlorosis and necrosis, which are intimately related to photosynthetic functions. Chlorophyll fluorescence lifetime measurement is a valuable noninvasive tool for analyzing photosynthetic processes and is a sensitive indicator of the environment surrounding the fluorescent molecules. In this study, our central goal was to explore the effect of viral infection on photosynthesis by employing chlorophyll fluorescence lifetime imaging (FLIM), steady-state fluorescence, non-photochemical quenching (NPQ), transmission electron microscopy (TEM), and pigment analysis. The data indicated that the chlorophyll fluorescence lifetime of chlorotic leaves was significantly shorter than that of healthy control leaves, and the fitted short lifetime component of chlorophyll fluorescence of chlorotic leaves was dominant. This dominant short lifetime component may result from damage to the structure of thylakoid, which was confirmed by TEM. The NPQ value of chlorotic leaves was slightly higher than that of healthy green leaves, which can be explained by increased neoxanthin, lutein and violaxanthin content relative to chlorophyll a. The difference in NPQ is slight, but FLIM can provide simple and direct characterization of PSII structure and photosynthetic function. Therefore, this technique shows great potential as a simple and rapid method for studying mechanisms of plant virus infection.

PDT dose dosimetry for Photofrin-mediated pleural photodynamic therapy (pPDT)

NASA Astrophysics Data System (ADS)

Ong, Yi Hong; Kim, Michele M.; Finlay, Jarod C.; Dimofte, Andreea; Singhal, Sunil; Glatstein, Eli; Cengel, Keith A.; Zhu, Timothy C.

2018-01-01

Photosensitizer fluorescence excited by photodynamic therapy (PDT) treatment light can be used to monitor the in vivo concentration of the photosensitizer and its photobleaching. The temporal integral of the product of in vivo photosensitizer concentration and light fluence is called PDT dose, which is an important dosimetry quantity for PDT. However, the detected photosensitizer fluorescence may be distorted by variations in the absorption and scattering of both excitation and fluorescence light in tissue. Therefore, correction of the measured fluorescence for distortion due to variable optical properties is required for absolute quantification of photosensitizer concentration. In this study, we have developed a four-channel PDT dose dosimetry system to simultaneously acquire light dosimetry and photosensitizer fluorescence data. We measured PDT dose at four sites in the pleural cavity during pleural PDT. We have determined an empirical optical property correction function using Monte Carlo simulations of fluorescence for a range of physiologically relevant tissue optical properties. Parameters of the optical property correction function for Photofrin fluorescence were determined experimentally using tissue-simulating phantoms. In vivo measurements of photosensitizer fluorescence showed negligible photobleaching of Photofrin during the PDT treatment, but large intra- and inter-patient heterogeneities of in vivo Photofrin concentration are observed. PDT doses delivered to 22 sites in the pleural cavity of 8 patients were different by 2.9 times intra-patient and 8.3 times inter-patient.

Realistic 3D computer model of the gerbil middle ear, featuring accurate morphology of bone and soft tissue structures.

PubMed

Buytaert, Jan A N; Salih, Wasil H M; Dierick, Manual; Jacobs, Patric; Dirckx, Joris J J

2011-12-01

In order to improve realism in middle ear (ME) finite-element modeling (FEM), comprehensive and precise morphological data are needed. To date, micro-scale X-ray computed tomography (μCT) recordings have been used as geometric input data for FEM models of the ME ossicles. Previously, attempts were made to obtain these data on ME soft tissue structures as well. However, due to low X-ray absorption of soft tissue, quality of these images is limited. Another popular approach is using histological sections as data for 3D models, delivering high in-plane resolution for the sections, but the technique is destructive in nature and registration of the sections is difficult. We combine data from high-resolution μCT recordings with data from high-resolution orthogonal-plane fluorescence optical-sectioning microscopy (OPFOS), both obtained on the same gerbil specimen. State-of-the-art μCT delivers high-resolution data on the 3D shape of ossicles and other ME bony structures, while the OPFOS setup generates data of unprecedented quality both on bone and soft tissue ME structures. Each of these techniques is tomographic and non-destructive and delivers sets of automatically aligned virtual sections. The datasets coming from different techniques need to be registered with respect to each other. By combining both datasets, we obtain a complete high-resolution morphological model of all functional components in the gerbil ME. The resulting 3D model can be readily imported in FEM software and is made freely available to the research community. In this paper, we discuss the methods used, present the resulting merged model, and discuss the morphological properties of the soft tissue structures, such as muscles and ligaments.

Sparsity Aware Adaptive Radar Sensor Imaging in Complex Scattering Environments

DTIC Science & Technology

2015-06-15

while meeting the requirement on the peak to average power ratio. Third, we study impact of waveform encoding on nonlinear electromagnetic tomographic...Enyue Lu. Time Domain Electromagnetic Tomography Using Propagation and Backpropagation Method, IEEE International Conference on Image Processing...Received Paper 3.00 4.00 Yuanwei Jin, Chengdon Dong, Enyue Lu. Waveform Encoding for Nonlinear Electromagnetic Tomographic Imaging, IEEE Global

An Analysis for Capital Expenditure Decisions at a Naval Regional Medical Center.

DTIC Science & Technology

1981-12-01

Service Equipment Review Committee 1. Portable defibrilator Computed tomographic scanner and cardioscope 2. ECG cart Automated blood cell counter 3. Gas...system sterilizer Gas system sterilizer 4. Automated blood cell Portable defibrilator and counter cardioscope 5. Computed tomographic ECG cart scanner...dictating and automated typing) systems. e. Filing equipment f. Automatic data processing equipment including data communications equipment. g

Analysis of 21-cm tomographic data

NASA Astrophysics Data System (ADS)

Mellema, Garrelt; Giri, Sambit; Ghara, Raghuna

2018-05-01

The future SKA1-Low radio telescope will be powerful enough to produce tomographic images of the 21-cm signal from the Epoch of Reionization. Here we address how to identify ionized regions in such data sets, taking into account the resolution and noise levels associated with SKA1-Low. We describe three methods of which one, superpixel oversegmentation, consistently performs best.

Research in Image Understanding as Applied to 3-D Microwave Tomographic Imaging with Near Optical Resolution.

DTIC Science & Technology

1986-03-10

and P. Frangos , "Inverse Scattering for Dielectric Media", Annual OSA Meeting, Wash. D.C., Oct. 1985. Invited Presentations 1. N. Farhat, "Tomographic...Optical Computing", DARPA Briefing, ~~April 1985. ... -7--.. , 1% If .% P . .% .% *-. 7777~14e 7-7. K-7 77 Theses 0 P.V. Frangos , "The Electromagnetic

Volume Segmentation and Ghost Particles

NASA Astrophysics Data System (ADS)

Ziskin, Isaac; Adrian, Ronald

2011-11-01

Volume Segmentation Tomographic PIV (VS-TPIV) is a type of tomographic PIV in which images of particles in a relatively thick volume are segmented into images on a set of much thinner volumes that may be approximated as planes, as in 2D planar PIV. The planes of images can be analysed by standard mono-PIV, and the volume of flow vectors can be recreated by assembling the planes of vectors. The interrogation process is similar to a Holographic PIV analysis, except that the planes of image data are extracted from two-dimensional camera images of the volume of particles instead of three-dimensional holographic images. Like the tomographic PIV method using the MART algorithm, Volume Segmentation requires at least two cameras and works best with three or four. Unlike the MART method, Volume Segmentation does not require reconstruction of individual particle images one pixel at a time and it does not require an iterative process, so it operates much faster. As in all tomographic reconstruction strategies, ambiguities known as ghost particles are produced in the segmentation process. The effect of these ghost particles on the PIV measurement is discussed. This research was supported by Contract 79419-001-09, Los Alamos National Laboratory.

Creating three-dimensional tooth models from tomographic images.

PubMed

Lima da Silva, Isaac Newton; Barbosa, Gustavo Frainer; Soares, Rodrigo Borowski Grecco; Beltrao, Maria Cecilia Gomes; Spohr, Ana Maria; Mota, Eduardo Golcalves; Oshima, Hugo Mitsuo Silva; Burnett, Luiz Henrique

2008-01-01

The use of Finite Element Analysis (FEA) is becoming very frequent in Dentistry. However, most of the three-dimensional models presented by the literature for teeth are limited in terms of geometry. Discrepancy in shape and dimensions can cause wrong results to occur. Sharp cusps and faceted contour can produce stress concentrations, which are incoherent with the reality. The aim of this study was the processing of tomographic images in order to develop an advanced three-dimensional reconstruction of the anatomy of a molar tooth and the integration of the resulting solid with commercially available CAD/CAE software. Computed tomographic images were obtained from 0.5 mm thick slices of mandibular molar and transferred to commercial cad software. Once the point cloud data have been generated, the work on these points started to get to the solid model of the tooth with Pro/Engineer software. The obtained tooth model showed very accurate shape and dimensions, as it was obtained from real tooth data with error of 0.0 to -0.8 mm. The methodology presented was efficient for creating a biomodel of a tooth from tomographic images that realistically represented its anatomy.

Experimental demonstration of laser tomographic adaptive optics on a 30-meter telescope at 800 nm

NASA Astrophysics Data System (ADS)

Ammons, S., Mark; Johnson, Luke; Kupke, Renate; Gavel, Donald T.; Max, Claire E.

2010-07-01

A critical goal in the next decade is to develop techniques that will extend Adaptive Optics correction to visible wavelengths on Extremely Large Telescopes (ELTs). We demonstrate in the laboratory the highly accurate atmospheric tomography necessary to defeat the cone effect on ELTs, an essential milestone on the path to this capability. We simulate a high-order Laser Tomographic AO System for a 30-meter telescope with the LTAO/MOAO testbed at UCSC. Eight Sodium Laser Guide Stars (LGSs) are sensed by 99x99 Shack-Hartmann wavefront sensors over 75". The AO system is diffraction-limited at a science wavelength of 800 nm (S ~ 6-9%) over a field of regard of 20" diameter. Openloop WFS systematic error is observed to be proportional to the total input atmospheric disturbance and is nearly the dominant error budget term (81 nm RMS), exceeded only by tomographic wavefront estimation error (92 nm RMS). The total residual wavefront error for this experiment is comparable to that expected for wide-field tomographic adaptive optics systems of similar wavefront sensor order and LGS constellation geometry planned for Extremely Large Telescopes.

Scalp marking for a craniotomy using a laser pointer during preoperative computed tomographic imaging: technical note.

PubMed

Kubo, S; Nakata, H; Sugauchi, Y; Yokota, N; Yoshimine, T

2000-05-01

The preoperative localization of superficial intracranial lesions is often necessary for accurate burr hole placement or craniotomy siting. It is not always easy, however, to localize the lesions over the scalp working only from computed tomographic images. We developed a simple method for such localization using a laser pointer during the preoperative computed tomographic examination. The angle of incidence, extending from a point on the scalp to the center of the computed tomographic image, is measured by the software included with the scanner. In the gantry, at the same angle as on the image, a laser is beamed from a handmade projector onto the patient's scalp toward the center of the gantry. The point illuminated on the patient's head corresponds to that on the image. The device and the method are described in detail herein. We applied this technique to mark the area for the craniotomy before surgery in five patients with superficial brain tumors. At the time of surgery, it was confirmed that the tumors were circumscribed precisely. The technique is easy to perform and useful in the preoperative planning for a craniotomy. In addition, the device is easily constructed and inexpensive.

Optical coherence tomography using images of hair structure and dyes penetrating into the hair.

PubMed

Tsugita, Tetsuya; Iwai, Toshiaki

2014-11-01

Hair dyes are commonly evaluated by the appearance of the hair after dyeing. However, this approach cannot simultaneously assess how deep the dye has penetrated into hair. For simultaneous assessment of the appearance and the interior of hair, we developed a visible-range red, green, and blue (RGB) (three primary colors)-optical coherence tomography (OCT) using an RGB LED light source. We then evaluated a phantom model based on the assumption that the sample's absorbability in the vertical direction affects the tomographic imaging. Consistent with theory, our device showed higher resolution than conventional OCT with far-red light. In the experiment on the phantom model, we confirmed that the tomographic imaging is affected by absorbability unique to the sample. Furthermore, we verified that permeability can be estimated from this tomographic image. We also identified for the first time the relationship between penetration of the dye into hair and characteristics of wavelength by tomographic imaging of dyed hair. We successfully simultaneously assessed the appearance of dyed hair and inward penetration of the dye without preparing hair sections. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

TomoBank: a tomographic data repository for computational x-ray science

NASA Astrophysics Data System (ADS)

De Carlo, Francesco; Gürsoy, Doğa; Ching, Daniel J.; Joost Batenburg, K.; Ludwig, Wolfgang; Mancini, Lucia; Marone, Federica; Mokso, Rajmund; Pelt, Daniël M.; Sijbers, Jan; Rivers, Mark

2018-03-01

There is a widening gap between the fast advancement of computational methods for tomographic reconstruction and their successful implementation in production software at various synchrotron facilities. This is due in part to the lack of readily available instrument datasets and phantoms representative of real materials for validation and comparison of new numerical methods. Recent advancements in detector technology have made sub-second and multi-energy tomographic data collection possible (Gibbs et al 2015 Sci. Rep. 5 11824), but have also increased the demand to develop new reconstruction methods able to handle in situ (Pelt and Batenburg 2013 IEEE Trans. Image Process. 22 5238-51) and dynamic systems (Mohan et al 2015 IEEE Trans. Comput. Imaging 1 96-111) that can be quickly incorporated in beamline production software (Gürsoy et al 2014 J. Synchrotron Radiat. 21 1188-93). The x-ray tomography data bank, tomoBank, provides a repository of experimental and simulated datasets with the aim to foster collaboration among computational scientists, beamline scientists, and experimentalists and to accelerate the development and implementation of tomographic reconstruction methods for synchrotron facility production software by providing easy access to challenging datasets and their descriptors.

Investigating structure–property relationships of biomineralized calcium phosphate compounds as fluorescent quenching–recovery platform

PubMed Central

Wang, Liuzheng; He, Xiang; Zhang, Wei; Liu, Yong; Zhang, Ying

2018-01-01

The structure–property relationship between biomineralized calcium phosphate compounds upon a fluorescent quenching–recovery platform and their distinct crystalline structure and surficial functional groups are investigated. A fluorescence-based sensing platform is shown to be viable for the sensing of 8-hydroxy-2-deoxy-guanosine in simulated systems. PMID:29515827

Development of Highly Fluorescent Materials Based on Thiophenylimidazole Dyes

NASA Technical Reports Server (NTRS)

Santos, Javier; Bu, Xiu R.; Mintz, Eric A.; Meador, Michael A. (Technical Monitor)

2000-01-01

Organic fluorescent materials are expected to find many potential applications in optical devices and photo-functionalized materials. Although many investigations have been focused on heterocyclic compounds such as coumarins, bipyridines, rhodamines, and pyrrole derivatives, little is known for fluorescent imidazole materials. We discovered that one particular class of imidazole derivatives is highly fluorescent. A series of monomeric and polymeric based fluorescent dyes were prepared containing a thiophene unit at the second position of the imidazole ring. Dependence of fluorescence efficiency on parameters such as solvent polarity and substituent groups has been investigated. It was found that a formyl group at the 2-position of the thiophene ring dramatically enhance fluorescence properties. Ion recognition probes indicated their potential as sensor materials. These fluorophores have flexibility for introduction of versatile substituent groups that could improve the fluorescence efficiency and sensor properties.

Fluorescence-based classification of Caribbean coral reef organisms and substrates

USGS Publications Warehouse

Zawada, David G.; Mazel, Charles H.

2014-01-01

A diverse group of coral reef organisms, representing several phyla, possess fluorescent pigments. We investigated the potential of using the characteristic fluorescence emission spectra of these pigments to enable unsupervised, optical classification of coral reef habitats. We compiled a library of characteristic fluorescence spectra through in situ and laboratory measurements from a variety of specimens throughout the Caribbean. Because fluorescent pigments are not species-specific, the spectral library is organized in terms of 15 functional groups. We investigated the spectral separability of the functional groups in terms of the number of wavebands required to distinguish between them, using the similarity measures Spectral Angle Mapper (SAM), Spectral Information Divergence (SID), SID-SAM mixed measure, and Mahalanobis distance. This set of measures represents geometric, stochastic, joint geometric-stochastic, and statistical approaches to classifying spectra. Our hyperspectral fluorescence data were used to generate sets of 4-, 6-, and 8-waveband spectra, including random variations in relative signal amplitude, spectral peak shifts, and water-column attenuation. Each set consisted of 2 different band definitions: ‘optimally-picked’ and ‘evenly-spaced.’ The optimally-picked wavebands were chosen to coincide with as many peaks as possible in the functional group spectra. Reference libraries were formed from half of the spectra in each set and used for training purposes. Average classification accuracies ranged from 76.3% for SAM with 4 evenly-spaced wavebands to 93.8% for Mahalanobis distance with 8 evenly-spaced wavebands. The Mahalanobis distance consistently outperformed the other measures. In a second test, empirically-measured spectra were classified using the same reference libraries and the Mahalanobis distance for just the 8 evenly-spaced waveband case. Average classification accuracies were 84% and 87%, corresponding to the extremes in modeled water-column attenuation. The classification results from both tests indicate that a high degree of separability among the 15 fluorescent-spectra functional groups is possible using only a modest number of spectral bands.

Ultra-compact fiber-optic two-photon microscope for functional fluorescence imaging in vivo.

PubMed

Engelbrecht, Christoph J; Johnston, Richard S; Seibel, Eric J; Helmchen, Fritjof

2008-04-14

We present a small, lightweight two-photon fiberscope and demonstrate its suitability for functional imaging in the intact brain. Our device consists of a hollow-core photonic crystal fiber for efficient delivery of near-IR femtosecond laser pulses, a spiral fiber-scanner for resonant beam steering, and a gradient-index lens system for fluorescence excitation, dichroic beam splitting, and signal collection. Fluorescence light is remotely detected using a standard photomultiplier tube. All optical components have 1 mm dimensions and the microscope's headpiece weighs only 0.6 grams. The instrument achieves micrometer resolution at frame rates of typically 25 Hz with a field-of-view of up to 200 microns. We demonstrate functional imaging of calcium signals in Purkinje cell dendrites in the cerebellum of anesthetized rats. The microscope will be easily portable by a rat or mouse and thus should enable functional imaging in freely behaving animals.

Using non-empirically tuned range-separated functionals with simulated emission bands to model fluorescence lifetimes.

PubMed

Wong, Z C; Fan, W Y; Chwee, T S; Sullivan, Michael B

2017-08-09

Fluorescence lifetimes were evaluated using TD-DFT under different approximations for the emitting molecule and various exchange-correlation functionals, such as B3LYP, BMK, CAM-B3LYP, LC-BLYP, M06, M06-2X, M11, PBE0, ωB97, ωB97X, LC-BLYP*, and ωB97X* where the range-separation parameters in the last two functionals were tuned in a non-empirical fashion. Changes in the optimised molecular geometries between the ground and electronically excited states were found to affect the quality of the calculated lifetimes significantly, while the inclusion of vibronic features led to further improvements over the assumption of a vertical electronic transition. The LC-BLYP* functional was found to return the most accurate fluorescence lifetimes with unsigned errors that are mostly within 1.5 ns of experimental values.

Functional Carbon Quantum Dots: A Versatile Platform for Chemosensing and Biosensing.

PubMed

Feng, Hui; Qian, Zhaosheng

2018-05-01

Carbon quantum dot has emerged as a new promising fluorescent nanomaterial due to its excellent optical properties, outstanding biocompatibility and accessible fabrication methods, and has shown huge application perspective in a variety of areas, especially in chemosensing and biosensing applications. In this personal account, we give a brief overview of carbon quantum dots from its origin and preparation methods, present some advance on fluorescence origin of carbon quantum dots, and focus on development of chemosensors and biosensors based on functional carbon quantum dots. Comprehensive advances on functional carbon quantum dots as a versatile platform for sensing from our group are included and summarized as well as some typical examples from the other groups. The biosensing applications of functional carbon quantum dots are highlighted from selective assays of enzyme activity to fluorescent identification of cancer cells and bacteria. © 2018 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Superparamagnetic nanoparticles for enhanced magnetic resonance and multimodal imaging

NASA Astrophysics Data System (ADS)

Sikma, Elise Ann Schultz

Magnetic resonance imaging (MRI) is a powerful tool for noninvasive tomographic imaging of biological systems with high spatial and temporal resolution. Superparamagnetic (SPM) nanoparticles have emerged as highly effective MR contrast agents due to their biocompatibility, ease of surface modification and magnetic properties. Conventional nanoparticle contrast agents suffer from difficult synthetic reproducibility, polydisperse sizes and weak magnetism. Numerous synthetic techniques and nanoparticle formulations have been developed to overcome these barriers. However, there are still major limitations in the development of new nanoparticle-based probes for MR and multimodal imaging including low signal amplification and absence of biochemical reporters. To address these issues, a set of multimodal (T2/optical) and dual contrast (T1/T2) nanoparticle probes has been developed. Their unique magnetic properties and imaging capabilities were thoroughly explored. An enzyme-activatable contrast agent is currently being developed as an innovative means for early in vivo detection of cancer at the cellular level. Multimodal probes function by combining the strengths of multiple imaging techniques into a single agent. Co-registration of data obtained by multiple imaging modalities validates the data, enhancing its quality and reliability. A series of T2/optical probes were successfully synthesized by attachment of a fluorescent dye to the surface of different types of nanoparticles. The multimodal nanoparticles generated sufficient MR and fluorescence signal to image transplanted islets in vivo. Dual contrast T1/T2 imaging probes were designed to overcome disadvantages inherent in the individual T1 and T2 components. A class of T1/T2 agents was developed consisting of a gadolinium (III) complex (DTPA chelate or DO3A macrocycle) conjugated to a biocompatible silica-coated metal oxide nanoparticle through a disulfide linker. The disulfide linker has the ability to be reduced in vivo by glutathione, releasing large payloads of signal-enhancing T1 probes into the surrounding environment. Optimization of the agent occurred over three sequential generations, with each generation addressing a new challenge. The result was a T2 nanoparticle containing high levels of conjugated T1 complex demonstrating enhanced MR relaxation properties. The probes created here have the potential to play a key role in the advancement of nanoparticle-based agents in biomedical MRI applications.

Optical gating with organic building blocks. A quantitative model for the fluorescence modulation of photochromic perylene bisimide dithienylcyclopentene triads

PubMed Central

Pärs, Martti; Gradmann, Michael; Gräf, Katja; Bauer, Peter; Thelakkat, Mukundan; Köhler, Jürgen

2014-01-01

We investigated the capability of molecular triads, consisting of two strong fluorophores that were covalently linked to a photochromic molecule, for optical gating. Therefore we monitored the fluorescence intensity of the fluorophores as a function of the isomeric state of the photoswitch. From the analysis of our data we develop a kinetic model that allows us to predict quantitatively the degree of the fluorescence modulation as a function of the mutual intensities of the lasers that are used to induce the fluorescence and the switching of the photochromic unit. We find that the achievable contrast for the modulation of the fluorescence depends mainly on the intensity ratio of the two light beams and appears to be very robust against absolute changes of these intensities. The latter result provides valuable information for the development of all-optical circuits which would require to handle different signal strengths for the input and output levels. PMID:24614963

Solvent dependent photophysical properties of dimethoxy curcumin

NASA Astrophysics Data System (ADS)

Barik, Atanu; Indira Priyadarsini, K.

2013-03-01

Dimethoxy curcumin (DMC) is a methylated derivative of curcumin. In order to know the effect of ring substitution on photophysical properties of curcumin, steady state absorption and fluorescence spectra of DMC were recorded in organic solvents with different polarity and compared with those of curcumin. The absorption and fluorescence spectra of DMC, like curcumin, are strongly dependent on solvent polarity and the maxima of DMC showed red shift with increase in solvent polarity function (Δf), but the above effect is prominently observed in case of fluorescence maxima. From the dependence of Stokes' shift on solvent polarity function the difference between the excited state and ground state dipole moment was estimated as 4.9 D. Fluorescence quantum yield (ϕf) and fluorescence lifetime (τf) of DMC were also measured in different solvents at room temperature. The results indicated that with increasing solvent polarity, ϕf increased linearly, which has been accounted for the decrease in non-radiative rate by intersystem crossing (ISC) processes.

Imaging intracellular pH in live cells with a genetically encoded red fluorescent protein sensor.

PubMed

Tantama, Mathew; Hung, Yin Pun; Yellen, Gary

2011-07-06

Intracellular pH affects protein structure and function, and proton gradients underlie the function of organelles such as lysosomes and mitochondria. We engineered a genetically encoded pH sensor by mutagenesis of the red fluorescent protein mKeima, providing a new tool to image intracellular pH in live cells. This sensor, named pHRed, is the first ratiometric, single-protein red fluorescent sensor of pH. Fluorescence emission of pHRed peaks at 610 nm while exhibiting dual excitation peaks at 440 and 585 nm that can be used for ratiometric imaging. The intensity ratio responds with an apparent pK(a) of 6.6 and a >10-fold dynamic range. Furthermore, pHRed has a pH-responsive fluorescence lifetime that changes by ~0.4 ns over physiological pH values and can be monitored with single-wavelength two-photon excitation. After characterizing the sensor, we tested pHRed's ability to monitor intracellular pH by imaging energy-dependent changes in cytosolic and mitochondrial pH.

Methods for Broadband Spectral Analysis: Intrinsic Fluorescence Temperature Sensing as an Example.

PubMed

Zhang, Weiwei; Wang, Guoyao; Baxter, Greg W; Collins, Stephen F

2017-06-01

A systematic study was performed on the temperature-dependent fluorescence of (Ba,Sr) 2 SiO 4 :Eu 2+ . The barycenter and extended intensity ratio techniques were proposed to characterize the broadband fluorescence spectra. These techniques and other known methods (listed below) were employed and compared in the fluorescent temperature sensing experiment. Multiple sensing functions were obtained using the behaviors of: (1) the barycenter location of the emission band; (2) the emission bandwidth; and (3) the ratio of intensities at different wavelengths in the emission band, respectively. The barycenter technique was not limited by the spectrometer resolution and worked well while the peak location method failed. All the sensing functions were based on the intrinsic characteristics of the fluorescence of the phosphor and demonstrated nearly linear relationships with temperature in the measuring range. The multifunctional temperature-sensing abilities of the phosphor can be applied in a point thermometer or thermal mapping. The new techniques were validated successfully for characterizing various spectra.

Ratiometric sensing of fluoride and acetate anions based on a BODIPY-azaindole platform and its application to living cell imaging.

PubMed

Mahapatra, Ajit Kumar; Maji, Rajkishor; Maiti, Kalipada; Adhikari, Susanta Sekhar; Das Mukhopadhyay, Chitrangada; Mandal, Debasish

2014-01-07

A new BODIPY-azaindole based fluorescent sensor 1 was designed and synthesized as a new colorimetric and ratiometric fluorescent chemosensor for fluoride. The binding and sensing abilities of sensor 1 towards various anions were studied by absorption, emission and (1)H NMR titration spectroscopies. The spectral responses of 1 to fluoride in acetonitrile-water were studied: an approximately 69 nm red shift in absorption and ratiometric fluorescent response was observed. The striking light yellow to deep brown color change in ambient light and green to blue emission color change are thought to be due to the deprotonation of the indole moiety of the azaindole fluorophore. From the changes in the absorption, fluorescence, and (1)H NMR titration spectra, proton-transfer mechanisms were deduced. Density function theory and time-dependent density function theory calculations were conducted to rationalize the optical response of the sensor. Results were supported by confocal fluorescence imaging and MTT assay of live cells.

Near-infrared fluorescence probes for enzymes based on binding affinity modulation of squarylium dye scaffold.

PubMed

Oushiki, Daihi; Kojima, Hirotatsu; Takahashi, Yuki; Komatsu, Toru; Terai, Takuya; Hanaoka, Kenjiro; Nishikawa, Makiya; Takakura, Yoshinobu; Nagano, Tetsuo

2012-05-15

We present a novel design strategy for near-infrared (NIR) fluorescence probes utilizing dye-protein interaction as a trigger for fluorescence enhancement. The design principle involves modification of a polymethine dye with cleavable functional groups that reduce the dye's protein-binding affinity. When these functional groups are removed by specific interaction with the target enzymes, the dye's protein affinity is restored, protein binding occurs, and the dye's fluorescence is strongly enhanced. To validate this strategy, we first designed and synthesized an alkaline phosphatase (ALP) sensor by introducing phosphate into the squarylium dye scaffold; this sensor was able to detect ALP-labeled secondary antibodies in Western blotting analysis. Second, we synthesized a probe for β-galactosidase (widely used as a reporter of gene expression) by means of β-galactosyl substitution of the squarylium scaffold; this sensor was able to visualize β-galactosidase activity both in vitro and in vivo. Our strategy should be applicable to obtain NIR fluorescence probes for a wide range of target enzymes.

An analog filter approach to frequency domain fluorescence spectroscopy

DOE PAGES

Trainham, Clifford P.; O'Neill, Mary D.; McKenna, Ian J.

2015-10-01

The rate equations found in frequency domain fluorescence spectroscopy are the same as those found in electronics under analog filter theory. Laplace transform methods are a natural way to solve the equations, and the methods can provide solutions for arbitrary excitation functions. The fluorescence terms can be modeled as circuit components and cascaded with drive and detection electronics to produce a global transfer function. Electronics design tools such as Spicea can be used to model fluorescence problems. In applications, such as remote sensing, where detection electronics are operated at high gain and limited bandwidth, a global modeling of the entiremore » system is important, since the filter terms of the drive and detection electronics affect the measured response of the fluorescence signals. Furthermore, the techniques described here can be used to separate signals from fast and slow fluorophores emitting into the same spectral band, and data collection can be greatly accelerated by means of a frequency comb driver waveform and appropriate signal processing of the response.« less

Fluorescence-tunable Ag-DNA biosensor with tailored cytotoxicity for live-cell applications

NASA Astrophysics Data System (ADS)

Bossert, Nelli; de Bruin, Donny; Götz, Maria; Bouwmeester, Dirk; Heinrich, Doris

2016-11-01

DNA-stabilized silver clusters (Ag-DNA) show excellent promise as a multi-functional nanoagent for molecular investigations in living cells. The unique properties of these fluorescent nanomaterials allow for intracellular optical sensors with tunable cytotoxicity based on simple modifications of the DNA sequences. Three Ag-DNA nanoagent designs are investigated, exhibiting optical responses to the intracellular environments and sensing-capability of ions, functional inside living cells. Their sequence-dependent fluorescence responses inside living cells include (1) a strong splitting of the fluorescence peak for a DNA hairpin construct, (2) an excitation and emission shift of up to 120 nm for a single-stranded DNA construct, and (3) a sequence robust in fluorescence properties. Additionally, the cytotoxicity of these Ag-DNA constructs is tunable, ranging from highly cytotoxic to biocompatible Ag-DNA, independent of their optical sensing capability. Thus, Ag-DNA represents a versatile live-cell nanoagent addressable towards anti-cancer, patient-specific and anti-bacterial applications.

A Project-Based Biochemistry Laboratory Promoting the Understanding and Uses of Fluorescence Spectroscopy in the Study of Biomolecular Structures and Interactions

ERIC Educational Resources Information Center

Briese, Nicholas; Jakubowsk, Henry V.

2007-01-01

A laboratory project for a first semester biochemistry course is described, which integrates the traditional classroom study of the structure and function of biomolecules with the laboratory study of these molecules using fluorescence spectroscopy. Students are assigned a specific question addressing the stability/function of lipids, proteins, or…

Correction Approach for Delta Function Convolution Model Fitting of Fluorescence Decay Data in the Case of a Monoexponential Reference Fluorophore.

PubMed

Talbot, Clifford B; Lagarto, João; Warren, Sean; Neil, Mark A A; French, Paul M W; Dunsby, Chris

2015-09-01

A correction is proposed to the Delta function convolution method (DFCM) for fitting a multiexponential decay model to time-resolved fluorescence decay data using a monoexponential reference fluorophore. A theoretical analysis of the discretised DFCM multiexponential decay function shows the presence an extra exponential decay term with the same lifetime as the reference fluorophore that we denote as the residual reference component. This extra decay component arises as a result of the discretised convolution of one of the two terms in the modified model function required by the DFCM. The effect of the residual reference component becomes more pronounced when the fluorescence lifetime of the reference is longer than all of the individual components of the specimen under inspection and when the temporal sampling interval is not negligible compared to the quantity (τR (-1) - τ(-1))(-1), where τR and τ are the fluorescence lifetimes of the reference and the specimen respectively. It is shown that the unwanted residual reference component results in systematic errors when fitting simulated data and that these errors are not present when the proposed correction is applied. The correction is also verified using real data obtained from experiment.

Surface functionalization of gold nanoparticles using hetero-bifunctional poly(ethylene glycol) spacer for intracellular tracking and delivery

PubMed Central

Shenoy, Dinesh; Fu, Wei; Li, Jane; Crasto, Curtis; Jones, Graham; DiMarzio, Charles; Sridhar, Srinivas; Amiji, Mansoor

2006-01-01

For the development of surface-functionalized gold nanoparticles as cellular probes and delivery agents, we have synthesized hetero-bifunctional poly(ethylene glycol) (PEG, MW 1500) having a thiol group on one terminus and a reactive functional group on the other for use as a flexible spacer. Coumarin, a model fluorescent dye, was conjugated to one end of the PEG spacer and gold nanoparticles were modified with coumarin-PEG-thiol. Surface attachment of coumarin through the PEG spacer decreased the fluorescence quenching effect of gold nanoparticles. The results of cellular cytotoxicity and fluorescence confocal analyses showed that the PEG spacer-modified nanoparticles were essentially non-toxic and could be efficiently internalized in the cells within 1 hour of incubation. Intracellular particle tracking using a Keck 3-D Fusion Microscope System showed that the functionalized gold nanoparticles were rapidly internalized in the cells and localized in the peri-nuclear region. Using the PEG spacer, the gold nano-platform can be conjugated with a variety of biologically relevant ligands such as fluorescent dyes, antibodies, etc in order to target, probe, and induce a stimulus at the target site. PMID:16467923

Impact of fluorescent protein fusions on the bacterial flagellar motor.

PubMed

Heo, M; Nord, A L; Chamousset, D; van Rijn, E; Beaumont, H J E; Pedaci, F

2017-10-03

Fluorescent fusion proteins open a direct and unique window onto protein function. However, they also introduce the risk of perturbation of the function of the native protein. Successful applications of fluorescent fusions therefore rely on a careful assessment and minimization of the side effects, but such insight is still lacking for many applications. This is particularly relevant in the study of the internal dynamics of motor proteins, where both the chemical and mechanical reaction coordinates can be affected. Fluorescent proteins fused to the stator of the Bacterial Flagellar Motor (BFM) have previously been used to unveil the motor subunit dynamics. Here we report the effects on single motors of three fluorescent proteins fused to the stators, all of which altered BFM behavior. The torque generated by individual stators was reduced while their stoichiometry remained unaffected. MotB fusions decreased the switching frequency and induced a novel bias-dependent asymmetry in the speed in the two directions. These effects could be mitigated by inserting a linker at the fusion point. These findings provide a quantitative account of the effects of fluorescent fusions to the stator on BFM dynamics and their alleviation- new insights that advance the use of fluorescent fusions to probe the dynamics of protein complexes.

Using artificial neural networks (ANN) for open-loop tomography

NASA Astrophysics Data System (ADS)

Osborn, James; De Cos Juez, Francisco Javier; Guzman, Dani; Butterley, Timothy; Myers, Richard; Guesalaga, Andres; Laine, Jesus

2011-09-01

The next generation of adaptive optics (AO) systems require tomographic techniques in order to correct for atmospheric turbulence along lines of sight separated from the guide stars. Multi-object adaptive optics (MOAO) is one such technique. Here, we present a method which uses an artificial neural network (ANN) to reconstruct the target phase given off-axis references sources. This method does not require any input of the turbulence profile and is therefore less susceptible to changing conditions than some existing methods. We compare our ANN method with a standard least squares type matrix multiplication method (MVM) in simulation and find that the tomographic error is similar to the MVM method. In changing conditions the tomographic error increases for MVM but remains constant with the ANN model and no large matrix inversions are required.

An inorganic/organic hybrid magnetic network as a colorimetric fluorescent nanosensor and its recognizing behavior toward Hg2+

NASA Astrophysics Data System (ADS)

Zeng, Xianfei; Xu, Yaohui; Chen, Xiumin; Ma, Wenhui; Zhou, Yang

2017-11-01

An inorganic/organic hybrid magnetic Fe3O4@SiO2 network functionalized with rhodamine derivatives was devised as a nanosensor for selective detection and removal of Hg2+ in this work. The inorganic/organic hybrid composites showed naked-eye color change in water/methanol media. The distinct color change on the surface of functionalized composite network was observed by separating and drying from aqueous solution after adsorbing Hg2+. The fluorescence spectra indicated that the functionalized nanosensor was highly sensitive and selective to Hg2+ in aqueous solution. Density functional theory (DFT) calculation was performed, which revealed a mechanism of fluorescence generated from Hg2+ induced desulfurization of rhodamine derivatives via forming new five-membered ring structure. The as-obtained composites not only had an excellent adsorption capability for Hg2+, but also showed a strong magnetic sensitivity, which allowed one to separate the functionalized magnetic nanocomposites from the solution.

2-Hydroxy-naphthyl functionalized mesoporous silica for fluorescence sensing and removal of aluminum ions.

PubMed

Das, Trisha; Roy, Ankita; Uyama, Hiroshi; Roy, Partha; Nandi, Mahasweta

2017-06-06

Mesoporous silica functionalized with a 2-hydroxy-naphthyl moiety has been synthesized and characterized by standard techniques like powder X-ray diffraction, N 2 adsorption/desorption studies, transmission electron microscopy and spectral studies like FT-IR, UV-visible, fluorescence and 13 C and 29 Si solid state NMR. The functionalized silica material showed significant enhancement in its emission intensity in the presence of Al 3+ ions whereas other metal ions could not bring about any increase in its emission intensity. They either quench the emission or do not alter the intensity significantly making the functionalized material a fluorescence chemosensor for Al 3+ . The sensitivity of the probe towards Al 3+ has been determined to be high with a low limit of detection value. As functionalized silica is not soluble in common solvents, it has been effectively used to bind and remove Al 3+ from a solution. Theoretical calculations on a model system have been performed to investigate the electronic spectral transitions.

Silica encapsulation of fluorescent nanodiamonds for colloidal stability and facile surface functionalization.

PubMed

Bumb, Ambika; Sarkar, Susanta K; Billington, Neil; Brechbiel, Martin W; Neuman, Keir C

2013-05-29

Fluorescent nanodiamonds (FNDs) emit in the near-IR and do not photobleach or photoblink. These properties make FNDs better suited for numerous imaging applications compared with commonly used fluorescence agents such as organic dyes and quantum dots. However, nanodiamonds do not form stable suspensions in aqueous buffer, are prone to aggregation, and are difficult to functionalize. Here we present a method for encapsulating nanodiamonds with silica using an innovative liposome-based encapsulation process that renders the particle surface biocompatible, stable, and readily functionalized through routine linking chemistries. Furthermore, the method selects for a desired particle size and produces a monodisperse agent. We attached biotin to the silica-coated FNDs and tracked the three-dimensional motion of a biotinylated FND tethered by a single DNA molecule with high spatial and temporal resolution.

About probabilistic integration of ill-posed geophysical tomography and logging data: A knowledge discovery approach versus petrophysical transfer function concepts illustrated using cross-borehole radar-, P- and S-wave traveltime tomography in combination with cone penetration and dielectric logging data

NASA Astrophysics Data System (ADS)

Paasche, Hendrik

2018-01-01

Site characterization requires detailed and ideally spatially continuous information about the subsurface. Geophysical tomographic experiments allow for spatially continuous imaging of physical parameter variations, e.g., seismic wave propagation velocities. Such physical parameters are often related to typical geotechnical or hydrological target parameters, e.g. as achieved from 1D direct push or borehole logging. Here, the probabilistic inference of 2D tip resistance, sleeve friction, and relative dielectric permittivity distributions in near-surface sediments is constrained by ill-posed cross-borehole seismic P- and S-wave and radar wave traveltime tomography. In doing so, we follow a discovery science strategy employing a fully data-driven approach capable of accounting for tomographic ambiguity and differences in spatial resolution between the geophysical tomograms and the geotechnical logging data used for calibration. We compare the outcome to results achieved employing classical hypothesis-driven approaches, i.e., deterministic transfer functions derived empirically for the inference of 2D sleeve friction from S-wave velocity tomograms and theoretically for the inference of 2D dielectric permittivity from radar wave velocity tomograms. The data-driven approach offers maximal flexibility in combination with very relaxed considerations about the character of the expected links. This makes it a versatile tool applicable to almost any combination of data sets. However, error propagation may be critical and justify thinking about a hypothesis-driven pre-selection of an optimal database going along with the risk of excluding relevant information from the analyses. Results achieved by transfer function rely on information about the nature of the link and optimal calibration settings drawn as retrospective hypothesis by other authors. Applying such transfer functions at other sites turns them into a priori valid hypothesis, which can, particularly for empirically derived transfer functions, result in poor predictions. However, a mindful utilization and critical evaluation of the consequences of turning a retrospectively drawn hypothesis into an a priori valid hypothesis can also result in good results for inference and prediction problems when using classical transfer function concepts.

Fluorescent fluid interface position sensor

DOEpatents

Weiss, Jonathan D.

2004-02-17

A new fluid interface position sensor has been developed, which is capable of optically determining the location of an interface between an upper fluid and a lower fluid, the upper fluid having a larger refractive index than a lower fluid. The sensor functions by measurement, of fluorescence excited by an optical pump beam which is confined within a fluorescent waveguide where that waveguide is in optical contact with the lower fluid, but escapes from the fluorescent waveguide where that waveguide is in optical contact with the upper fluid.

REVIEWS OF TOPICAL PROBLEMS: Nonlinear dynamics of the brain: emotion and cognition

NASA Astrophysics Data System (ADS)

Rabinovich, Mikhail I.; Muezzinoglu, M. K.

2010-07-01

Experimental investigations of neural system functioning and brain activity are standardly based on the assumption that perceptions, emotions, and cognitive functions can be understood by analyzing steady-state neural processes and static tomographic snapshots. The new approaches discussed in this review are based on the analysis of transient processes and metastable states. Transient dynamics is characterized by two basic properties, structural stability and information sensitivity. The ideas and methods that we discuss provide an explanation for the occurrence of and successive transitions between metastable states observed in experiments, and offer new approaches to behavior analysis. Models of the emotional and cognitive functions of the brain are suggested. The mathematical object that represents the observed transient brain processes in the phase space of the model is a structurally stable heteroclinic channel. The possibility of using the suggested models to construct a quantitative theory of some emotional and cognitive functions is illustrated.

A Fast Hermite Transform★

PubMed Central

Leibon, Gregory; Rockmore, Daniel N.; Park, Wooram; Taintor, Robert; Chirikjian, Gregory S.

2008-01-01

We present algorithms for fast and stable approximation of the Hermite transform of a compactly supported function on the real line, attainable via an application of a fast algebraic algorithm for computing sums associated with a three-term relation. Trade-offs between approximation in bandlimit (in the Hermite sense) and size of the support region are addressed. Numerical experiments are presented that show the feasibility and utility of our approach. Generalizations to any family of orthogonal polynomials are outlined. Applications to various problems in tomographic reconstruction, including the determination of protein structure, are discussed. PMID:20027202

Joint measurement of complementary observables in moment tomography

NASA Astrophysics Data System (ADS)

Teo, Yong Siah; Müller, Christian R.; Jeong, Hyunseok; Hradil, Zdeněk; Řeháček, Jaroslav; Sánchez-Soto, Luis L.

Wigner and Husimi quasi-distributions, owing to their functional regularity, give the two archetypal and equivalent representations of all observable-parameters in continuous-variable quantum information. Balanced homodyning (HOM) and heterodyning (HET) that correspond to their associated sampling procedures, on the other hand, fare very differently concerning their state or parameter reconstruction accuracies. We present a general theory of a now-known fact that HET can be tomographically more powerful than balanced homodyning to many interesting classes of single-mode quantum states, and discuss the treatment for two-mode sources.

A malonitrile-functionalized metal-organic framework for hydrogen sulfide detection and selective amino acid molecular recognition

NASA Astrophysics Data System (ADS)

Li, Haiwei; Feng, Xiao; Guo, Yuexin; Chen, Didi; Li, Rui; Ren, Xiaoqian; Jiang, Xin; Dong, Yuping; Wang, Bo

2014-03-01

A novel porous polymeric fluorescence probe, MN-ZIF-90, has been designed and synthesized for quantitative hydrogen sulfide (H2S) fluorescent detection and highly selective amino acid recognition. This distinct crystalline structure, derived from rational design and malonitrile functionalization, can trigger significant enhancement of its fluorescent intensity when exposed to H2S or cysteine molecules. Indeed this new metal-organic framework (MOF) structure shows high selectivity of biothiols over other amino acids and exhibits favorable stability. Moreover, in vitro viability assays on HeLa cells show low cytotoxicity of MN-ZIF-90 and its imaging contrast efficiency is further demonstrated by fluorescence microscopy studies. This facile yet powerful strategy also offers great potential of using open-framework materials (i.e. MOFs) as the novel platform for sensing and other biological applications.

Expression of gamma-aminobutyric acid rho 1 and rho 1 Delta 450 as gene fusions with the green fluorescent protein.

PubMed

Martinez-Torres, A; Miledi, R

2001-02-13

The functional characteristics and cellular localization of the gamma aminobutyric acid (GABA) rho 1 receptor and its nonfunctional isoform rho 1 Delta 450 were investigated by expressing them as gene fusions with the enhanced version of the green fluorescent protein (GFP). Oocytes injected with rho 1-GFP had receptors that gated chloride channels when activated by GABA. The functional characteristics of these receptors were the same as for those of wild-type rho 1 receptors. Fluorescence, because of the chimeric receptors expressed, was over the whole oocyte but was more intense near the cell surface and more abundant in the animal hemisphere. Similar to the wild type, rho 1 Delta 450-GFP did not lead to the expression of functional GABA receptors, and injected oocytes failed to generate currents even after exposure to high concentrations of GABA. Nonetheless, the fluorescence displayed by oocytes expressing rho 1 Delta 450-GFP was distributed similarly to that of rho 1-GFP. Mammalian cells transfected with the rho 1-GFP or rho 1 Delta 450-GFP constructs showed mostly intracellularly distributed fluorescence in confocal microscope images. A sparse localization of fluorescence was observed in the plasma membrane regardless of the cell line used. We conclude that rho 1 Delta 450 is expressed and transported close to, and perhaps incorporated into, the plasma membrane. Thus, rho 1- and rho 1 Delta 450-GFP fusions provide a powerful tool to visualize the traffic of GABA type C receptors.

On the origin of non-exponential fluorescence decays in enzyme-ligand complex

NASA Astrophysics Data System (ADS)

Wlodarczyk, Jakub; Kierdaszuk, Borys

2004-05-01

Complex fluorescence decays have usually been analyzed with the aid of a multi-exponential model, but interpretation of the individual exponential terms has not been adequately characterized. In such cases the intensity decays were also analyzed in terms of the continuous lifetime distribution as a consequence of an interaction of fluorophore with environment, conformational heterogeneity or their dynamical nature. We show that non-exponential fluorescence decay of the enzyme-ligand complexes may results from time dependent energy transport. The latter, to our opinion, may be accounted for by electron transport from the protein tyrosines to their neighbor residues. We introduce the time-dependent hopping rate in the form v(t)~(a+bt)-1. This in turn leads to the luminescence decay function in the form I(t)=Ioexp(-t/τ1)(1+lt/γτ2)-γ. Such a decay function provides good fits to highly complex fluorescence decays. The power-like tail implies the time hierarchy in migration energy process due to the hierarchical energy-level structure. Moreover, such a power-like term is a manifestation of so called Tsallis nonextensive statistic and is suitable for description of the systems with long-range interactions, memory effect as well as with fluctuations of characteristic lifetime of fluorescence. The proposed decay function was applied in analysis of fluorescence decays of tyrosine protein, i.e. the enzyme purine nucleoside phosphorylase from E. coli in a complex with formycin A (an inhibitor) and orthophosphate (a co-substrate).

Optical Sensing of Aromatic Amino Acids and Dipeptides by a Crown-Ether-Functionalized Perylene Bisimide Fluorophore.

PubMed

Weißenstein, Annike; Saha-Möller, Chantu R; Würthner, Frank

2018-06-04

The host-guest binding properties of a fluorescent perylene bisimide (PBI) receptor equipped with crown ether were studied in detail with a series of aromatic amino acids and dipeptides by UV/Vis, fluorescence and NMR spectroscopy. Fluorescence titration experiments showed that electron-rich aromatic amino acids and dipeptides strongly quench the fluorescence of the electron-poor PBI host molecule. Benesi-Hildebrand plots of fluorescence titration data confirmed the formation of host-guest complexes with 1:2 stoichiometry. Binding constants determined by global analysis of UV/Vis and fluorescence titration experiments revealed values between 10 3  m -1 and 10 5  m -1 in acetonitrile/methanol (9:1) at 23 °C. These data showed that amino acid l-Trp having an indole group and dipeptides containing this amino acid bind to the PBI receptor more strongly than other amino acids and dipeptides investigated here. For dipeptides containing l-Trp or l-Tyr, the binding strength is dependent on the distance between the ammonium group and the aromatic unit of the amino acids and dipeptides leading to a strong sensitivity for Ala-Trp dipeptide. 1D and 2D NMR experiments also corroborated 1:2 host-guest complexation and indicated formation of two diastereomeric species of host-guest complexes. The studies have shown that a properly functionalized PBI fluorophore functions as a molecular probe for the optical sensing of aromatic amino acids and dipeptides. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

A nanodiamond-fluorescein conjugate for cell studies

NASA Astrophysics Data System (ADS)

Pedroso-Santana, Seidy; Fleitas-Salazar, Noralvis; Sarabia-Sainz, Andrei; Silva-Campa, Erika; Burgara-Estrella, Alexel; Angulo-Molina, Aracely; Melendrez, Rodrigo; Pedroza-Montero, Martin; Riera, Raul

2018-03-01

The use of nanodiamonds in studies with living systems generally involves the modification of their surfaces with functional groups. Fluorescent molecules can be attached to these groups, so that one can know the exact position of the particles in each moment of the interaction with the cells. Here we modify the surface of detonation nanodiamonds and nitrogen-vacancy center nanodiamonds using carboxylation and hydroxylation procedures. Subsequent reactions with silicates and cysteine, before addition of fluorescein allow to obtain fluorescent nano-conjugates. We used confocal microscopy to observe the position of nanodiamonds interacting with HeLa cells. At 3 h post-incubation the green fluorescence is localized in extracellular rounded like-vesicles assemblies while at 24 h the conjugates can be observed inside the cells. The measurement of the fluorescence emitted by both conjugates allowed to find an enhanced emission of fluorescein isothiocyanate (FITC) when the nitrogen-vacancy center is present. We propose the existence of a fluorescence enhancement by electron transference process. The procedure described in this work allows the functionalization of nanodiamonds with FITC and other molecules using functional surface groups and small size mediators. Also, as was proved in our work, the nanodiamond-fluorescein conjugates can be used to track nanoparticles position within the cell. Localization studies are particularly important for drug delivery applications of nanodiamonds.

A novel hNIS/tdTomato fusion reporter for visualizing the relationship between the cellular localization of sodium iodide symporter and its iodine uptake function under heat shock treatment.

PubMed

Yeom, Chan Joo; Chung, Taemoon; Youn, Hyewon; Kang, Keon Wook; Lee, Dong Soo; Chung, June-Key

2015-01-01

The function of membrane-localized sodium iodide symporter (NIS) determines the efficacy of radioiodine therapy in thyroid cancer. Here, we describe a dual mode reporter fused with human NIS (hNIS) and a red fluorescent protein named tandem dimeric Tomato (tdTomato) for the in vitro and in vivo imaging of hNIS protein expression, localization, and iodide uptake function. Human cervical epithelial adenocarcinoma cell line (HeLa)-hNIS/tdTomato cells were established by transducing a fusion gene expressing hNIS/tdTomato under the control of a cytomegalovirus promoter. Fluorescence imaging, confocal microscopy, and an 125I uptake assay were performed to validate the integrity of the fusion protein. Actinomycin D and cycloheximide were used to block newly synthesized hNIS proteins. In vivo images were acquired using a gamma camera and a Maestro fluorescence imaging device. The fluorescence intensity of membrane-localized hNIS and 125I uptake both were increased after heat shock. Scintigraphy and fluorescence imaging indicated specific accumulation of the hNIS/tdTomato fusion protein in xenografted tumors, supporting the utility of this system for in vivo monitoring of hNIS expression and activity. We developed a novel hNIS/tdTomato dual mode reporter that enables visualization of the expression, localization, and iodine uptake function of hNIS in vitro and in vivo.

ReAsH/FlAsH Labeling and Image Analysis of Tetracysteine Sensor Proteins in Cells

PubMed Central

Irtegun, Sevgi; Ramdzan, Yasmin M.; Mulhern, Terrence D.; Hatters, Danny M.

2011-01-01

Fluorescent proteins and dyes are essential tools for the study of protein trafficking, localization and function in cells. While fluorescent proteins such as green fluorescence protein (GFP) have been extensively used as fusion partners to proteins to track the properties of a protein of interest1, recent developments with smaller tags enable new functionalities of proteins to be examined in cells such as conformational change and protein-association 2, 3. One small tag system involves a tetracysteine motif (CCXXCC) genetically inserted into a target protein, which binds to biarsenical dyes, ReAsH (red fluorescent) and FlAsH (green fluorescent), with high specificity even in live cells 2. The TC/biarsenical dye system offers far less steric constraints to the host protein than fluorescent proteins which has enabled several new approaches to measure conformational change and protein-protein interactions 4-7. We recently developed a novel application of TC tags as sensors of oligomerization in cells expressing mutant huntingtin, which when mutated aggregates in neurons in Huntington disease 7. Huntingtin was tagged with two fluorescent dyes, one a fluorescent protein to track protein location, and the second a TC tag which only binds biarsenical dyes in monomers. Hence, changes in colocalization between protein and biarsenical dye reactivity enabled submicroscopic oligomer content to be spatially mapped within cells. Here, we describe how to label TC-tagged proteins fused to a fluorescent protein (Cherry, GFP or CFP) with FlAsH or ReAsH in live mammalian cells and how to quantify the two color fluorescence (Cherry/FlAsH, CFP/FlAsH or GFP/ReAsH combinations). PMID:21897361

Tomographic Image Reconstruction Using an Interpolation Method for Tree Decay Detection

Treesearch

Hailin Feng; Guanghui Li; Sheng Fu; Xiping Wang

2014-01-01

Stress wave velocity has been traditionally regarded as an indicator of the extent of damage inside wood. This paper aimed to detect internal decay of urban trees through reconstructing tomographic image of the cross section of a tree trunk. A grid model covering the cross section area of a tree trunk was defined with some assumptions. Stress wave data were processed...

Far-red fluorescent probes for canonical and non-canonical nucleic acid structures: current progress and future implications.

PubMed

Suseela, Y V; Narayanaswamy, Nagarjun; Pratihar, Sumon; Govindaraju, Thimmaiah

2018-02-05

The structural diversity and functional relevance of nucleic acids (NAs), mainly deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), are indispensable for almost all living organisms, with minute aberrations in their structure and function becoming causative factors in numerous human diseases. The standard structures of NAs, termed canonical structures, are supported by Watson-Crick hydrogen bonding. Under special physiological conditions, NAs adopt distinct spatial organisations, giving rise to non-canonical conformations supported by hydrogen bonding other than the Watson-Crick type; such non-canonical structures have a definite function in controlling gene expression and are considered as novel diagnostic and therapeutic targets. Development of molecular probes for these canonical and non-canonical DNA/RNA structures has been an active field of research. Among the numerous probes studied, probes with turn-on fluorescence in the far-red (600-750 nm) region are highly sought-after due to minimal autofluorescence and cellular damage. Far-red fluorescent probes are vital for real-time imaging of NAs in live cells as they provide good resolution and minimal perturbation of the cell under investigation. In this review, we present recent advances in the area of far-red fluorescent probes of DNA/RNA and non-canonical G-quadruplex structures. For the sake of continuity and completeness, we provide a brief overview of visible fluorescent probes. Utmost importance is given to design criteria, characteristic properties and biological applications, including in cellulo imaging, apart from critical discussion on limitations of the far-red fluorescent probes. Finally, we offer current and future prospects in targeting canonical and non-canonical NAs specific to cellular organelles, through sequence- and conformation-specific far-red fluorescent probes. We also cover their implications in chemical and molecular biology, with particular focus on decoding various disease mechanisms involving NAs.

Detection of rheumatoid arthritis by evaluation of normalized variances of fluorescence time correlation functions

NASA Astrophysics Data System (ADS)

Dziekan, Thomas; Weissbach, Carmen; Voigt, Jan; Ebert, Bernd; MacDonald, Rainer; Bahner, Malte L.; Mahler, Marianne; Schirner, Michael; Berliner, Michael; Berliner, Birgitt; Osel, Jens; Osel, Ilka

2011-07-01

Fluorescence imaging using the dye indocyanine green as a contrast agent was investigated in a prospective clinical study for the detection of rheumatoid arthritis. Normalized variances of correlated time series of fluorescence intensities describing the bolus kinetics of the contrast agent in certain regions of interest were analyzed to differentiate healthy from inflamed finger joints. These values are determined using a robust, parameter-free algorithm. We found that the normalized variance of correlation functions improves the differentiation between healthy joints of volunteers and joints with rheumatoid arthritis of patients by about 10% compared to, e.g., ratios of areas under the curves of raw data.

Fluorescent Probes for Single-Step Detection and Proteomic Profiling of Histone Deacetylases.

PubMed

Xie, Yusheng; Ge, Jingyan; Lei, Haipeng; Peng, Bo; Zhang, Huatang; Wang, Danyang; Pan, Sijun; Chen, Ganchao; Chen, Lanfang; Wang, Yi; Hao, Quan; Yao, Shao Q; Sun, Hongyan

2016-12-07

Histone deacetylases (HDACs) play important roles in regulating various physiological and pathological processes. Developing fluorescent probes capable of detecting HDAC activity can help further elucidate the roles of HDACs in biology. In this study, we first developed a set of activity-based fluorescent probes by incorporating the Kac residue and the O-NBD group. Upon enzymatic removal of the acetyl group in the Kac residue, the released free amine reacted intramolecularly with the O-NBD moiety, resulting in turn-on fluorescence. These designed probes are capable of detecting HDAC activity in a continuous fashion, thereby eliminating the extra step of fluorescence development. Remarkably, the amount of turn-on fluorescence can be as high as 50-fold, which is superior to the existing one-step HDAC fluorescent probes. Inhibition experiments further proved that the probes can serve as useful tools for screening HDAC inhibitors. Building on these results, we moved on and designed a dual-purpose fluorescent probe by introducing a diazirine photo-cross-linker into the probe. The resulting probe was not only capable of reporting enzymatic activity but also able to directly identify and capture the protein targets from the complex cellular environment. By combining a fluorometric method and in-gel fluorescence scanning technique, we found that epigenetic readers and erasers can be readily identified and differentiated using a single probe. This is not achievable with traditional photoaffinity probes. In light of the prominent properties and the diverse functions of this newly developed probe, we envision that it can provide a robust tool for functional analysis of HDACs and facilitate future drug discovery in epigenetics.

Laser induced fluorescence technique for detecting organic matter in East China Sea

NASA Astrophysics Data System (ADS)

Chen, Peng; Wang, Tianyu; Pan, Delu; Huang, Haiqing

2017-10-01

A laser induced fluorescence (LIF) technique for fast diagnosing chromophoric dissolved organic matter (CDOM) in water is discussed. We have developed a new field-portable laser fluorometer for rapid fluorescence measurements. In addtion, the fluorescence spectral characteristics of fluorescent constituents (e.g., CDOM, chlorophyll-a) were analyzed with a spectral deconvolution method of bi-Gaussian peak function. In situ measurements by the LIF technique compared well with values measured by conventional spectrophotometer method in laboratory. A significant correlation (R2 = 0.93) was observed between fluorescence by the technique and absorption by laboratory spectrophotometer. Influence of temperature variation on LIF measurement was investigated in lab and a temperature coefficient was deduced for fluorescence correction. Distributions of CDOM fluorescence measured using this technique in the East China Sea coast were presented. The in situ result demonstrated the utility of the LIF technique for rapid detecting dissolved organic matter.

Synthesis of novel taspine diphenyl derivatives as fluorescence probes and inhibitors of breast cancer cell proliferation.

PubMed

He, Huaizhen; Zhan, Yingzhuan; Zhang, Yanmin; Zhang, Jie; He, Langchong

2012-01-01

Two novel taspine diphenyl derivatives (Ta-dD) were designed and synthesized by introducing different coumarin fluorescent groups into the basic structure of Ta-dD. The main advantage of these two compounds is that they can be used as fluorescence probes and inhibitors simultaneously. In the present study, the fluorescent properties of the probes were measured and their inhibition of four breast cancer cell lines was tested. Different concentrations of the fluorescence probe were added to MCF-7 breast cancer cells for fluorescence imaging analysis under normal conditions. The results suggested that both of the new compounds have not only fluorescence but also the ability to inhibit effects on different breast cancer cell lines, which indicates their possible further use as dual functional fluorescence probes in tracer analysis. Copyright © 2011 John Wiley & Sons, Ltd.

Towards Seismic Tomography Based Upon Adjoint Methods

NASA Astrophysics Data System (ADS)

Tromp, J.; Liu, Q.; Tape, C.; Maggi, A.

2006-12-01

We outline the theory behind tomographic inversions based on 3D reference models, fully numerical 3D wave propagation, and adjoint methods. Our approach involves computing the Fréchet derivatives for tomographic inversions via the interaction between a forward wavefield, propagating from the source to the receivers, and an `adjoint' wavefield, propagating from the receivers back to the source. The forward wavefield is computed using a spectral-element method (SEM) and a heterogeneous wave-speed model, and stored as synthetic seismograms at particular receivers for which there is data. We specify an objective or misfit function that defines a measure of misfit between data and synthetics. For a given receiver, the differences between the data and the synthetics are time reversed and used as the source of the adjoint wavefield. For each earthquake, the interaction between the regular and adjoint wavefields is used to construct finite-frequency sensitivity kernels, which we call event kernel. These kernels may be thought of as weighted sums of measurement-specific banana-donut kernels, with weights determined by the measurements. The overall sensitivity is simply the sum of event kernels, which defines the misfit kernel. The misfit kernel is multiplied by convenient orthonormal basis functions that are embedded in the SEM code, resulting in the gradient of the misfit function, i.e., the Fréchet derivatives. The misfit kernel is multiplied by convenient orthonormal basis functions that are embedded in the SEM code, resulting in the gradient of the misfit function, i.e., the Fréchet derivatives. A conjugate gradient algorithm is used to iteratively improve the model while reducing the misfit function. Using 2D examples for Rayleigh wave phase-speed maps of southern California, we illustrate the construction of the gradient and the minimization algorithm, and consider various tomographic experiments, including source inversions, structural inversions, and joint source-structure inversions. We also illustrate the characteristics of these 3D finite-frequency kernels based upon adjoint simulations for a variety of global arrivals, e.g., Pdiff, P'P', and SKS, and we illustrate how the approach may be used to investigate body- and surface-wave anisotropy. In adjoint tomography any time segment in which the data and synthetics match reasonably well is suitable for measurement, and this implies a much greater number of phases per seismogram can be used compared to classical tomography in which the sensitivity of the measurements is determined analytically for specific arrivals, e.g., P. We use an automated picking algorithm based upon short-term/long-term averages and strict phase and amplitude anomaly criteria to determine arrivals and time windows suitable for measurement. For shallow global events the algorithm typically identifies of the order of 1000~windows suitable for measurement, whereas for a deep event the number can reach 4000. For southern California earthquakes the number of phases is of the order of 100 for a magnitude 4.0 event and up to 450 for a magnitude 5.0 event. We will show examples of event kernels for both global and regional earthquakes. These event kernels form the basis of adjoint tomography.

Estrogen receptor-targeted optical imaging of breast cancer cells with near-infrared fluorescent dye

NASA Astrophysics Data System (ADS)

Jose, Iven; Deodhar, Kodand; Chiplunkar, Shuba V.; Patkar, Meena

2010-02-01

Molecular imaging provides the in vivo characterization of cellular molecular events involved in normal and pathologic processes. With the advent of optical molecular imaging, specific molecules, proteins and genes may be tagged with a luminescent reporter and visualized in small animals. This powerful new tool has pushed in vivo optical imaging to the forefront as it allows for direct determination of drug bio-distribution and uptake kinetics as well as an indicator of biochemical activity and drug efficacy. Although optical imaging encompasses diverse techniques and makes use of various wavelengths of light, a great deal of excitement in molecular research lies in the use of tomographic and fluorescence techniques to image living tissues with near-infrared (NIR) light. Nonionizing, noninvasive near-infrared optical imaging has great potential to become promising alternative for breast cancer detection. Fluorescence spectroscopy studies of human tissue suggest that a variety of lesions show distinct fluorescence spectra compared to those of normal tissue. It has also been shown that exogenous dyes exhibit selective uptake in neoplastic lesions and may offer the best contrast for optical imaging. Use of exogenous agents would provide fluorescent markers, which could serve to detect embedded tumors in the breast. In particular, the ability to monitor the fluorescent yield and lifetime may also enable biochemical specificity if the fluorophore is sensitive to a specific metabolite, such as oxygen. As a first step, we have synthesized and characterized one such NIR fluorescent dye conjugate, which could potentially be used to detect estrogen receptors (ER)[2] . The conjugate was synthesized by ester formation between 17-β estradiol and a hydrophilic derivative of indocyanine green (ICG) cyanine dye, bis-1, 1-(4-sulfobutyl) indotricarbocyanine-5- carboxylic acid, sodium salt. The ester formed was found to have an extra binding ability with the receptor cites as compared to ICG, which was established by the partition coefficient studies. The replacement of the sodium ion in the ester by a larger glucosammonium ion was found to enhance the hydrophilicity and reduce the toxic effect on the cell lines. The excitation and emission peaks for the conjugate were recorded in the NIR region as 750nm and 788nm respectively. The ester was found nontoxic on adenocarcinoma breast cancer cell lines MCF-7/MDA-MB-231. Specific binding and endocytosis of the estrogen-labeled conjugate was studied on the MCF-7 (ER positive) and MDA-MB-231 (ER negative). Conjugate staining of MCF-7 cells showed ~ 4-fold increase in signal intensity compared to MDA-MB- 231. Further, estrogen molecules were found to be specifically localized to the nuclear region of MCF-7 cells, whereas MDA-MB-231 showed plasma membrane staining. This technique offers the potential of noninvasive detection of hormone receptor status in breast cancer cells and would help in decreasing the load of unnecessary biopsies. Here, we have reported the progress made in the development of a novel NIR external contrast agent and the work is in progress to use this conjugate for the molecular based, diagnostic imaging of breast cancer.

Imaging of Brain Slices with a Genetically Encoded Voltage Indicator.

PubMed

Quicke, Peter; Barnes, Samuel J; Knöpfel, Thomas

2017-01-01

Functional fluorescence microscopy of brain slices using voltage sensitive fluorescent proteins (VSFPs) allows large scale electrophysiological monitoring of neuronal excitation and inhibition. We describe the equipment and techniques needed to successfully record functional responses optical voltage signals from cells expressing a voltage indicator such as VSFP Butterfly 1.2. We also discuss the advantages of voltage imaging and the challenges it presents.

A dual-function fluorescent probe for monitoring the degrees of hypoxia in living cells via the imaging of nitroreductase and adenosine triphosphate.

PubMed

Fang, Yu; Shi, Wen; Hu, Yiming; Li, Xiaohua; Ma, Huimin

2018-05-24

A new dual-function fluorescent probe is developed for detecting nitroreductase (NTR) and adenosine triphosphate (ATP) with different responses. Imaging application of the probe reveals that intracellular NTR and ATP display an adverse changing trend during a hypoxic process and ATP can serve as a new sign for cell hypoxia.

A charge transfer amplified fluorescent Hg2+ complex for detection of picric acid and construction of logic functions.

PubMed

Kumar, Manoj; Reja, Shahi Imam; Bhalla, Vandana

2012-12-07

A chemosensor 3 based on the N,N-dimethylaminocinnamaldehyde has been synthesized which shows fluorescence turn-on response with Hg(2+) ions, and the in situ prepared 3-Hg(2+) complex has been used for detection of picric acid via electrostatic interaction and construction of a combinatorial logic circuit with NOR and INHIBIT logic functions.

Enhanced Combined Tomography and Biomechanics Data for Distinguishing Forme Fruste Keratoconus.

PubMed

Luz, Allan; Lopes, Bernardo; Hallahan, Katie M; Valbon, Bruno; Ramos, Isaac; Faria-Correia, Fernando; Schor, Paulo; Dupps, William J; Ambrósio, Renato

2016-07-01

To evaluate the performance of the Ocular Response Analyzer (ORA) (Reichert Ophthalmic Instruments, Depew, NY) variables and Pentacam HR (Oculus Optikgeräte GmbH, Wetzlar, Germany) tomographic parameters in differentiating forme fruste keratoconus (FFKC) from normal corneas, and to assess a combined biomechanical and tomographic parameter to improve outcomes. Seventy-six eyes of 76 normal patients and 21 eyes of 21 patients with FFKC were included in the study. Fifteen variables were derived from exported ORA signals to characterize putative indicators of biomechanical behavior and 37 ORA waveform parameters were tested. Sixteen tomographic parameters from Pentacam HR were tested. Logistic regression was used to produce a combined biomechanical and tomography linear model. Differences between groups were assessed by the Mann-Whitney U test. The area under the receiver operating characteristics curve (AUROC) was used to compare diagnostic performance. No statistically significant differences were found in age, thinnest point, central corneal thickness, and maximum keratometry between groups. Twenty-one parameters showed significant differences between the FFKC and control groups. Among the ORA waveform measurements, the best parameters were those related to the area under the first peak, p1area1 (AUROC, 0.717 ± 0.065). Among the investigator ORA variables, a measure incorporating the pressure-deformation relationship of the entire response cycle was the best predictor (hysteresis loop area, AUROC, 0.688 ± 0.068). Among tomographic parameters, Belin/Ambrósio display showed the highest predictive value (AUROC, 0.91 ± 0.057). A combination of parameters showed the best result (AUROC, 0.953 ± 0.024) outperforming individual parameters. Tomographic and biomechanical parameters demonstrated the ability to differentiate FFKC from normal eyes. A combination of both types of information further improved predictive value. [J Refract Surg. 2016;32(7):479-485.]. Copyright 2016, SLACK Incorporated.

Tomographic reconstruction of heat release rate perturbations induced by helical modes in turbulent swirl flames

NASA Astrophysics Data System (ADS)

Moeck, Jonas P.; Bourgouin, Jean-François; Durox, Daniel; Schuller, Thierry; Candel, Sébastien

2013-04-01

Swirl flows with vortex breakdown are widely used in industrial combustion systems for flame stabilization. This type of flow is known to sustain a hydrodynamic instability with a rotating helical structure, one common manifestation of it being the precessing vortex core. The role of this unsteady flow mode in combustion is not well understood, and its interaction with combustion instabilities and flame stabilization remains unclear. It is therefore important to assess the structure of the perturbation in the flame that is induced by this helical mode. Based on principles of tomographic reconstruction, a method is presented to determine the 3-D distribution of the heat release rate perturbation associated with the helical mode. Since this flow instability is rotating, a phase-resolved sequence of projection images of light emitted from the flame is identical to the Radon transform of the light intensity distribution in the combustor volume and thus can be used for tomographic reconstruction. This is achieved with one stationary camera only, a vast reduction in experimental and hardware requirements compared to a multi-camera setup or camera repositioning, which is typically required for tomographic reconstruction. Different approaches to extract the coherent part of the oscillation from the images are discussed. Two novel tomographic reconstruction algorithms specifically tailored to the structure of the heat release rate perturbations related to the helical mode are derived. The reconstruction techniques are first applied to an artificial field to illustrate the accuracy. High-speed imaging data acquired in a turbulent swirl-stabilized combustor setup with strong helical mode oscillations are then used to reconstruct the 3-D structure of the associated perturbation in the flame.

Permeability Surface of Deep Middle Cerebral Artery Territory on Computed Tomographic Perfusion Predicts Hemorrhagic Transformation After Stroke.

PubMed

Li, Qiao; Gao, Xinyi; Yao, Zhenwei; Feng, Xiaoyuan; He, Huijin; Xue, Jing; Gao, Peiyi; Yang, Lumeng; Cheng, Xin; Chen, Weijian; Yang, Yunjun

2017-09-01

Permeability surface (PS) on computed tomographic perfusion reflects blood-brain barrier permeability and is related to hemorrhagic transformation (HT). HT of deep middle cerebral artery (MCA) territory can occur after recanalization of proximal large-vessel occlusion. We aimed to determine the relationship between HT and PS of deep MCA territory. We retrospectively reviewed 70 consecutive acute ischemic stroke patients presenting with occlusion of the distal internal carotid artery or M1 segment of the MCA. All patients underwent computed tomographic perfusion within 6 hours after symptom onset. Computed tomographic perfusion data were postprocessed to generate maps of different perfusion parameters. Risk factors were identified for increased deep MCA territory PS. Receiver operating characteristic curve analysis was performed to calculate the optimal PS threshold to predict HT of deep MCA territory. Increased PS was associated with HT of deep MCA territory. After adjustments for age, sex, onset time to computed tomographic perfusion, and baseline National Institutes of Health Stroke Scale, poor collateral status (odds ratio, 7.8; 95% confidence interval, 1.67-37.14; P =0.009) and proximal MCA-M1 occlusion (odds ratio, 4.12; 95% confidence interval, 1.03-16.52; P =0.045) were independently associated with increased deep MCA territory PS. Relative PS most accurately predicted HT of deep MCA territory (area under curve, 0.94; optimal threshold, 2.89). Increased PS can predict HT of deep MCA territory after recanalization therapy for cerebral proximal large-vessel occlusion. Proximal MCA-M1 complete occlusion and distal internal carotid artery occlusion in conjunction with poor collaterals elevate deep MCA territory PS. © 2017 American Heart Association, Inc.

Fluorescent porous film modified polymer optical fiber via "click" chemistry: stable dye dispersion and trace explosive detection.

PubMed

Ma, Jiajun; Lv, Ling; Zou, Gang; Zhang, Qijin

2015-01-14

In this paper, we report a facile strategy to fabricate fluorescent porous thin film on the surface of U-bent poly(methyl methacrylate) optical fiber (U-bent POF) in situ via "click" polymerization for vapor phase sensing of explosives. Upon irradiation of evanescent UV light transmitting within the fiber under ambient condition, a porous film (POSS-thiol cross-linking film, PTCF) is synthesized on the side surface of the fiber by a thiol-ene "click" reaction of vinyl-functionalized polyhedral oligomeric silsesquioxanes (POSS-V8) and alkane dithiols. When vinyl-functionalized porphyrin, containing four allyl substituents at the periphery, is added into precursors for the polymerization, fluorescence porphyrin can be covalently bonded into the cross-linked network of PTCF. This "fastened" way reduces the aggregation-induced fluorescence self-quenching of porphyrin and enhances the physicochemical stability of the porous film on the surface of U-bent POF. Fluorescent signals of the PTCF/U-bent POF probe made by this method exhibit high fluorescence quenching toward trace TNT and DNT vapor and the highest fluorescence quenching efficiency is observed for 1, 6-hexanedimercaptan-based film. In addition, because of the presence of POSS-V8 with multi cross-linkable groups, PTCF exhibits well-organized pore network and stable dye dispersion, which not only causes fast and sensitive fluorescence quenching against vapors of nitroaromatic compounds, but also provides a repeatability of the probing performance.