| 1. |
- Andersson-Engels, Stefan, et al.
(författare)
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In vivo luminescence imaging and tomography using upconverting nanoparticles as contrast agents
- 2012
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Ingår i: 2012 Asia Communications and Photonics Conference. - 2162-108X. ; , s. 2-3
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Konferensbidrag (refereegranskat)abstract
- Upconverting nanoparticles have recently drawn increasingly attention as contrast agents for optical bioimaging. They enable autofluorescence-free imaging within the tissue optical window, and improved spatial resolution as compared to conventional fluorescence-based contrast agents. (C) 2012 Optical Society of America
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| 2. |
- Johagen, Daniel, et al.
(författare)
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A microscopic view of gaseous microbubbles passing a filter screen
- 2017
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Ingår i: International Journal of Artificial Organs. - : Wichtig Publishing. - 0391-3988 .- 1724-6040. ; 40:9, s. 498-502
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The aim of this study was to investigate the filtration efficacy of a 38-µm 1-layer screen filter based on Doppler registrations and video recordings of gaseous microbubbles (GME) observed in a microscope.Methods: The relative filtration efficacy (RFE) was calculated from 20 (n = 20) sequential bursts of air introduced into the Plasmodex® primed test circuit.Results: The main findings indicate that the RFE decreased (p = 0.00), with increasing flow rates (100-300 mL/min) through the filter screen. This reaction was most accentuated for GME below the size of 100 µm, where counts of GME paradoxically increased after filtration, indicating GME fragmentation. For GME sized between 100-250 µm, the RFE was constantly >60%, independently of the flow rate level. The video recording documenting the GME interactions with the screen filter confirmed the experimental findings.Conslusions: The 38-µm 1-layer screen filter investigated in this experimental setup was unable to trap gaseous microbubbles effectively, especially for GME below 100 µm in size and in conjunction with high flow rates.
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| 3. |
- Abualhoul, Mohammad Y., et al.
(författare)
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Free space optical link for biomedical applications
- 2012
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Ingår i: Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS. - 1557-170X. - 9781424441198 ; , s. 1667-1670
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Konferensbidrag (refereegranskat)abstract
- Free space optics is an interesting alternative for telemetry with medical implants, due to the high data bandwidths available at optical frequencies. Especially implanted brain-computer interfaces gives rise to large data sets that needs to be transmitted transcutaneous. In this paper we show that it is possible to establish such a link at near-IR wavelengths using a modulated reflector in the implant, thus keeping the laser and the detector on the outside. In addition, we show that it will not only work on short, i.e. touch, distances but also at larger distances, in the range of a meter. We have used an electro absorption modulator to modulate the reflection of an external laser source back towards an external detector. The only part of this system that needs to be implanted is the modulator and drive electronics. The study has been done both by Monte-Carlo simulations of a multi-layer model of a rat skull, and with an experiment demonstrating the feasibility of the link when transmitted through biological tissue. The results show that it is possible to establish a transcutaneous link with an external laser source and light detector, and an internal modulated reflector.
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| 4. |
- Cheng, Haynes P. H., et al.
(författare)
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Autofluorescence of pigmented skin lesions using a pulsed UV laser
- 2010
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Ingår i: Proceedings of SPIE. - : SPIE. ; 7715, s. 1-77151
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Konferensbidrag (refereegranskat)abstract
- We report preliminary clinical results of autofluorescence imaging of malignant and benign skin lesions, using pulsed 355 nm laser excitation with synchronized detection. The novel synchronized detection system allows high signal-tonoise ratio to be achieved in the resulting autofluorescence signal, which may in turn produce high contrast images that improve diagnosis, even in the presence of ambient room light. The synchronized set-up utilizes a compact, diode pumped, pulsed UV laser at 355 nm which is coupled to a CCD camera and a liquid crystal tunable filter. The excitation and image capture is sampled at 5 kHz and the resulting autofluorescence is captured with the liquid crystal filter cycling through seven wavelengths between 420 nm and 580 nm. The clinical study targets pigmented skin lesions and evaluates the prospects of using autofluorescence as a possible means in differentiating malignant and benign skin tumors. Up to now, sixteen patients have participated in the clinical study. The autofluorescence images, averaged over the exposure time of one second, will be presented along with histopathological results. Initial survey of the images show good contrast and diagnostic results show promising agreement based on the histopathological results.
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| 5. |
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| 6. |
- Krohn, Jorgen, et al.
(författare)
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Transscleral Optical Spectroscopy of Uveal Melanoma in Enucleated Human Eyes
- 2012
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Ingår i: Investigative Ophthalmology & Visual Science. - : Association for Research in Vision and Ophthalmology (ARVO). - 1552-5783. ; 53:9, s. 5379-5385
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE. The aims of this study were to use transscleral optical spectroscopy to analyze normal and tumor-infiltrated areas of enucleated human eyes, and to characterize the spectral properties of uveal melanomas in relation to various morphological features. METHODS. Nine consecutive eyes enucleated for uveal melanoma were examined by transscleral spectroscopy, using a fiber-optic probe that exerted a fixed pressure on the scleral surface. Spectroscopic measurements, covering the wavelength range of 400-1100 nm, were sequentially performed over the uveal melanoma and on the opposite (normal) side of each eye. The eyes were then processed for histological and immunohistochemical analyses. Comparisons between spectral and morphological parameters were performed by Spearman's rank correlation coefficient and unpaired t-test. RESULTS. The average reflection intensity obtained from the normal side of the eyes was higher than that from the tumors. The spectral imprint of hemoglobin was lower and that of water was considerably stronger when compared with the tumor side. The diffuse reflection spectra from the melanomas showed a strong correlation with the degree of tumor pigmentation (Spearman's rho = -0.87, P < 0.0001). A weaker correlation was observed between the amount of hemoglobin-related absorption and the density of intratumoral blood vessels (Spearman's rho = -0.25, P = 0.023). The mean diffuse reflection intensity obtained from the spindle cell melanomas was significantly higher than that from the mixed and epithelioid cell melanomas (P < 0.0001). CONCLUSIONS. Although future in vivo studies are required, these data suggest that transscleral optical spectroscopy is a feasible method for identification and morphological assessment of choroidal tumors. (Invest Ophthalmol Vis Sci. 2012;53:5379-5385) DOI: 10.1167/iovs.12-9840
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| 7. |
- Krohn, Jorgen, et al.
(författare)
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Transscleral visible/near-infrared spectroscopy for quantitative assessment of melanin in a uveal melanoma phantom of ex vivo porcine eyes
- 2010
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Ingår i: Experimental Eye Research. - : Elsevier BV. - 0014-4835. ; 90:2, s. 330-336
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Tidskriftsartikel (refereegranskat)abstract
- Optical spectroscopy has been used as a supplement to conventional techniques for analyzing and diagnosing cancer in many human organs. Because ocular tumors may be characterized by their different melanin content, we investigated the feasibility of using transscleral visible/near-infrared spectroscopy (Vis/NIRS) to estimate the quantity of melanin in a novel uveal melanoma phantom of ex vivo porcine eyes. The phantoms were made by injecting a freshly prepared suspension of 15% (wt/vol) gelatin, 10 mg/ml titanium dioxide (TiO2), and natural melanin, isolated from the ink sac of cuttlefish (Sepia officinalis), into the suprachoroidal space of 30 enucleated porcine eyes. The melanin concentrations used were 1 mg/ml, 2 mg/ml, and 3 mg/ml, with 10 eyes in each group. After gelation, the size and location of the phantoms were documented by B-scan ultrasonography and transillumination. Vis/NIRS recordings, covering the wavelength region from 550 to 1000 nm, were performed with two optical fibers separated by 6 mm to deliver and collect the light through the sclera. During all measurements, the exact pressure exerted by the fiber probe on the scleral surface was monitored by placing the eye on an electronic scale. Transscleral Vis/NIRS was performed across the phantom inclusion, as well as on the opposite (normal) side of each eye. A total of three consecutive measurements were carried out alternately on each side of the globe. The spectral data were analyzed using partial least squares regression. In the melanin concentration groups of 1 mg/ml (n = 10), 2 mg/ml (n = 10), and 3 mg/ml (n 10), the largest basal phantom diameters (mean +/- SD) were 14.9 +/- 1.6 mm, 14.6 +/- 1.5 mm, and 14.3 +/- 1.0 mm, respectively (p > 0.05). The largest phantom thicknesses (mean +/- SD) were 4.0 +/- 0.5 mm, 4.4 +/- 0.7 mm, and 4.5 +/- 0.5 mm, respectively (p > 0.05). Statistical regression modeling of the Vis/NIRS data revealed that it was possible to correctly classify the phantoms according to their melanin concentrations in 84.4% of cases. The correct classification rate for phantoms with the lowest (1 mg/ml) and highest (3 mg/ml) melanin concentrations was 99.2%. The study demonstrates that transscleral Vis/NIRS is a feasible and accurate method for predicting the content of melanin in choroidal lesions. (C) 2009 Elsevier Ltd. All rights reserved.
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| 8. |
- Madru, Renata, et al.
(författare)
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Development of a Hybrid Nanoprobe for Triple-Modality MR/SPECT/Optical Fluorescence Imaging
- 2014
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Ingår i: Diagnostics. - : MDPI AG. - 2075-4418. ; 4:1, s. 13-26
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Tidskriftsartikel (refereegranskat)abstract
- Hybrid clinical imaging is an emerging technology, which improves disease diagnosis by combining already existing technologies. With the combination of high-resolution morphological imaging, i.e., MRI/CT, and high-sensitive molecular detection offered by SPECT/PET/Optical, physicians can detect disease progression at an early stage and design patient-specific treatments. To fully exploit the possibilities of hybrid imaging a hybrid probe compatible with each imaging technology is required. Here, we present a hybrid nanoprobe for triple modality MR/SPECT/Fluorescence imaging. Our imaging agent is comprised of superparamagnetic iron oxide nanoparticles (SPIONs), labeled with 99mTc and an Alexa fluorophore (AF), together forming 99mTc-AF-SPIONs. The agent was stable in human serum, and, after subcutaneous injection in the hind paw of Wistar rats, showed to be highly specific by accumulating in the sentinel lymph node. All three modalities clearly visualized the imaging agent. Our results show that a single imaging agent can be used for hybrid imaging. The use of a single hybrid contrast agent permits simultaneous hybrid imaging and, more conventionally, allow for single modality imaging at different time points. For example, a hybrid contrast agent enables pre-operative planning, intra-operative guidance, and post-operative evaluation with the same contrast agent.Keywords: SPION, SPECT, optical, fluorescence imaging, magnetic resonance imaging, MR, SLN
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| 9. |
- Spaulding, Caitlin N., et al.
(författare)
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Functional role of the type 1 pilus rod structure in mediating host-pathogen interactions
- 2018
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Ingår i: eLIFE. - : eLife Sciences Publications. - 2050-084X. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Uropathogenic E. coli (UPEC), which cause urinary tract infections (UTI), utilize type 1 pili, a chaperone usher pathway (CUP) pilus, to cause UTI and colonize the gut. The pilus rod, comprised of repeating FimA subunits, provides a structural scaffold for displaying the tip adhesin, FimH. We solved the 4.2 Å resolution structure of the type 1 pilus rod using cryo-electron microscopy. Residues forming the interactive surfaces that determine the mechanical properties of the rod were maintained by selection based on a global alignment of fimA sequences. We identified mutations that did not alter pilus production in vitro but reduced the force required to unwind the rod. UPEC expressing these mutant pili were significantly attenuated in bladder infection and intestinal colonization in mice. This study elucidates an unappreciated functional role for the molecular spring-like property of type 1 pilus rods in host-pathogen interactions and carries important implications for other pilus-mediated diseases.
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| 10. |
- Stangner, Tim, et al.
(författare)
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Cooke-Triplet-Tweezers : More compact, robust and efficient optical tweezers
- 2018
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Ingår i: Optics Letters. - 0146-9592 .- 1539-4794. ; 43:9, s. 1990-1993
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Tidskriftsartikel (refereegranskat)abstract
- We present a versatile three-lens optical design to improve the overall compactness, efficiency, and robustness for optical tweezers based applications. The design, inspired by the Cooke–Triplet configuration, allows for continuous beam magnifications of 2–10× , and axial as well as lateral focal shifts can be realized without switching lenses or introducing optical aberrations. We quantify the beam quality and trapping stiffness and compare the Cooke–Triplet design with the commonly used double Kepler design through simulations and direct experiments. Optical trapping of 1 and 2 μm beads shows that the Cooke–Triplet possesses an equally strong optical trap stiffness compared to the double Kepler lens design but reduces its lens system length by a factor of 2.6. Finally, we demonstrate how a Twyman–Green interferometer integrated in the Cooke–Triplet optical tweezers setup provides a fast and simple method to characterize the wavefront aberrations in the lens system and how it can help in aligning the optical components perfectly.
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