| 1. |
- Bunke, Josefine, et al.
(författare)
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Photoacoustic imaging for the monitoring of local changes in oxygen saturation following an adrenaline injection in human forearm skin
- 2021
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Ingår i: Biomedical Optics Express. - 2156-7085. ; 12:7, s. 4084-4096
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Tidskriftsartikel (refereegranskat)abstract
- Clinical monitoring of blood oxygen saturation (sO2) is traditionally performed using optical techniques, such as pulse oximetry and diffuse reflectance spectroscopy (DRS), which lack spatial resolution. Photoacoustic imaging (PAI) is a rapidly developing biomedical imaging technique that is superior to previous techniques in that it combines optical excitation and acoustic detection, providing a map of chromophore distribution in the tissue. Hitherto, PAI has primarily been used in preclinical studies, and only a few studies have been performed in patients. Its ability to measure sO2 with spatial resolution during local vasoconstriction after adrenaline injection has not yet been investigated. Using PAI and spectral unmixing we characterize the heterogeneous change in sO2 after injecting a local anesthetic containing adrenaline into the dermis on the forearm of seven healthy subjects. In comparison to results obtained using DRS, we highlight contrasting results obtained between the two methods arising due to the so-called ‘window effect’ caused by a reduced blood flow in the superficial vascular plexus. The results demonstrate the importance of spatially resolving sO2 and the ability of PAI to assess the tissue composition in different layers of the skin.
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| 2. |
- Dahlstrand, Ulf, et al.
(författare)
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Photoacoustic imaging for three-dimensional visualization and delineation of basal cell carcinoma in patients
- 2020
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Ingår i: Photoacoustics. - : Elsevier BV. - 2213-5979. ; 18
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Tidskriftsartikel (refereegranskat)abstract
- Background: Photoacoustic (PA) imaging is an emerging non-invasive biomedical imaging modality that could potentially be used to determine the borders of basal cell carcinomas (BCC) preoperatively in order to reduce the need for repeated surgery.Methods: Two- and three-dimensional PA images were obtained by scanning BCCs using 59 wavelengths in the range 680-970 nm. Spectral unmixing was performed to visualize the tumor tissue distribution. Spectral signatures from 38 BCCs and healthy tissue were compared ex vivo.Results and discussion: The PA spectra could be used to differentiate between BCC and healthy tissue ex vivo (p < 0.05). Spectral unmixing provided visualization of the overall architecture of the lesion and its border.Conclusion: PA imaging can be used to differentiate between BCC and healthy tissue and can potentially be used to delineate tumors prior to surgical excision.
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| 3. |
- Gesslein, Bodil, et al.
(författare)
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Comparison of perimetric 24-2 and 30-2 test patterns in detecting visual field defects in patients with tumours in the pituitary region
- 2024
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Ingår i: Acta Ophthalmologica. - 1755-3768. ; 102:3, s. 326-333
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Automated perimetry provides a standardized method of measuring the visual field. The Humphrey Field Analyser (HFA) uses the 24-2 test pattern to cover 24 degrees centrally or the 30-2 test pattern to cover a slightly broader region of 30 degrees. The aim of this study was to determine whether the 24-2 test pattern provides comparable information to the 30-2 test pattern in detecting visual field defects in patients with tumours in the pituitary region.METHODS: A retrospective cohort study was carried out on patients with tumours in the pituitary region and radiologically confirmed compression of the visual pathway. Included patients (79 of 133) had been examined using the Humphrey 30-2 visual field test, after which the 30-2 test patterns were reduced into corresponding 24-2 test patterns. The location of visual field defects, visual acuity and the perimetric parameters mean deviation (MD) and visual field index (VFI) were also recorded.RESULTS: No patient was classified differently when evaluated with the 24-2 test pattern, compared to the 30-2 test pattern. Interestingly, although the majority of patients had visual field defects located in the temporal visual field of each eye, a significant minority did not. In addition, it was found that a large proportion of patients had normal visual acuity (≥0.8).CONCLUSIONS: The use of the HFA 24-2 test pattern reliably detected visual field defects in patients with tumours in the pituitary region. The present study indicates that MD and VFI are not reliable parameters for evaluating visual field defects due to compression.
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| 4. |
- Gesslein, Bodil
(författare)
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Effects of Ischaemia on the Neuroretina and Retinal Blood Vessels
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Identification of the intracellular signal transduction pathways activated in retinal ischaemia may be important in revealing novel pharmacological targets. The retinal blood vessels are key organs in circulatory failure, and in this work the retinal vasculature was therefore examined separately from the neuroretina. The porcine eye has a typical primate-like architecture and is similar to the human eye regarding its size and retinal blood supply. The arteries in the porcine eye are large enough to allow dissection, and can be used for both functional and molecular analysis. Therefore, the first aim of this work was to set up and evaluate a porcine model of pressure-induced retinal ischaemia-reperfusion injury. The second aim was to study the intracellular signal transduction pathways activated in retinal ischaemia, including mitogen-activated protein kinases (MAPKs), protein kinase C (PKC), tumour necrosis factor (TNF), hypoxia-inducible factor (HIF) and vascular endothelial growth factor (VEGF). The results show that the porcine model of retinal ischaemia-reperfusion was successfully established, and that retinal blood vessels and the neuroretina could be studied separately. The retinal circulation was completely obstructed at an intra ocular pressure of 80 mmHg, and fluorescein angiography during reperfusion showed how the circulation was restored. Changes were seen in multifocal electroretinograms following the ischaemic insult, showing decreased amplitudes and increased implicit times. Pyknotic cell nuclei count, TUNEL-positive cells and glial fibrillary acidic protein mRNA expression were increased as a result of ischaemia, suggesting retinal injury and glial cell activation. The expression of signalling pathways including MAPKs, PKC, TNF, HIF and VEGF was altered in both the neuroretina and retinal arteries, in a way that is typical of ischaemia. These are intracellular signalling molecules that may be important in the development of retinal injury following ischaemia, and may thus be interesting targets for the development of pharmacological therapeutic agents.
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| 5. |
- Gesslein, Bodil, et al.
(författare)
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Mitogen-activated protein kinases in the porcine retinal arteries and neuroretina following retinal ischemia-reperfusion.
- 2010
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Ingår i: Molecular Vision. - 1090-0535. ; 16, s. 392-407
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The aim of the present study was to examine changes in the expression of intracellular signal-transduction pathways, specifically mitogen-activated protein kinases, following retinal ischemia-reperfusion. METHODS: Retinal ischemia was induced by elevating the intraocular pressure in porcine eyes, followed by 5, 12, or 20 h of reperfusion. The results were compared to those of the sham- operated fellow eye. The retinal arteries and neuroretina were isolated separately and examined. Tissue morphology and DNA fragmentation were studied using histology. Extracellular signal-regulated kinase 1 and 2 (ERK1/2), p38, c-junNH(2)-terminal kinases (JNK), and c-jun protein and mRNA expression were examined using immunofluorescence staining, western blot, and real-time PCR techniques. RESULTS: Pyknotic cell nuclei, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive cells, and glial fibrillary acidic protein mRNA expression were increased in ischemia, suggesting injury. Phosphorylated ERK1/2 protein levels were increased in the neuroretina following ischemia, while mRNA levels were unaltered. p38 protein and mRNA levels were not affected by ischemia. Immunofluorescence staining for phosphorylated p38 was especially intense in the retinal blood vessels, while only weak in the neuroretina. Phosphorylated JNK protein and mRNA were slightly decreased in ischemia. Phosphorylated c-jun protein and mRNA levels were higher in the neuroretina after ischemia-reperfusion. CONCLUSIONS: Retinal ischemia-reperfusion alters expression of mitogen-activated protein kinases, particularly ERK1/2, in the neuroretina and retinal arteries. The development of pharmacological treatment targeting these intracellular transduction pathways may prevent injury to the eye following retinal circulatory failure.
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| 6. |
- Gesslein, Bodil, et al.
(författare)
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Protein kinase C in porcine retinal arteries and neuroretina following retinal ischemia-reperfusion.
- 2009
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Ingår i: Molecular Vision. - 1090-0535. ; 15:Apr 13, s. 737-746
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Identification of the intracellular signal-transduction pathways activated in retinal ischemia may be important in revealing novel pharmacological targets. To date, most studies have focused on identifying neuroprotective agents. The retinal blood vessels are key organs in circulatory failure, and this study was therefore designed to examine the retinal vasculature separately from the neuroretina. METHODS: Retinal ischemia was induced by elevating the intraocular pressure in porcine eyes, followed by 5, 12, or 20 h of reperfusion. Protein kinase C (PKC)alpha, PKCbeta1, and PKCbeta2 mRNA levels, and protein expression were determined using real-time PCR, western blot, and immunofluorescence staining techniques. RESULTS: The retinal arteries could easily be dissected free and studied separately from the neuroretina in this porcine model. The PKCalpha, PKCbeta1, and PKCbeta2 mRNA levels tended to be lower in ischemia-reperfused than in sham-operated eyes in both the retinal arteries and the neuroretina. This was most prominent after 5 h, and less pronounced after 12 h and 20 h of reperfusion. Likewise, the protein levels of PKCalpha, PKCbeta1, and PKCbeta2 were slightly lower following ischemia-reperfusion when compared to sham-operated eyes. PKCalpha, PKCbeta1, and PKCbeta2 immunostaining were observed in bipolar cells of the neuroretina and in endothelial cells, and to a low extent in the smooth muscle layer, of the retinal arteries. CONCLUSIONS: Retinal ischemia followed by reperfusion results in lower levels of PKC in both the neuroretina and retinal arteries. New targets for pharmacological treatment may be found by studying the retinal vasculature so as to identify the intracellular signal-transduction pathways involved in the development of injury following retinal circulatory failure.
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| 7. |
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| 8. |
- Hult, Jenny, et al.
(författare)
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Comparison of photoacoustic imaging and histopathological examination in determining the dimensions of 52 human melanomas and nevi ex vivo : Biomedical Optics Express
- 2021
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Ingår i: Biomedical Optics Express. - 2156-7085. ; 12:7, s. 4097-4114
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Tidskriftsartikel (refereegranskat)abstract
- Surgical excision followed by histopathological examination is the gold standard for the diagnosis and staging of melanoma. Reoperations and unnecessary removal of healthy tissue could be reduced if non-invasive imaging techniques were available for presurgical tumor delineation. However, no technique has gained widespread clinical use to date due to shallow imaging depth or the absence of functional imaging capability. Photoacoustic (PA) imaging is a novel technology that combines the strengths of optical and ultrasound imaging to reveal the molecular composition of tissue at high resolution. Encouraging results have been obtained from previous animal and human studies on melanoma, but there is still a lack of clinical data. This is the largest study of its kind to date, including 52 melanomas and nevi. 3D multiwavelength PA scanning was performed ex vivo, using 59 excitation wavelengths from 680 nm to 970 nm. Spectral unmixing over this broad wavelength range, accounting for the absorption of several tissue chromophores, provided excellent contrast between healthy tissue and tumor. Combining the results of spectral analysis with spatially resolved information provided a map of the tumor borders in greater detail than previously reported. The tumor dimensions determined with PA imaging were strongly correlated with those determined by histopathological examination for both melanomas and nevi.
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| 9. |
- Hult, Jenny, et al.
(författare)
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Unique spectral signature of human cutaneous squamous cell carcinoma by photoacoustic imaging
- 2020
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Ingår i: Journal of Biophotonics. - : Wiley. - 1864-063X .- 1864-0648. ; 13:5
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Tidskriftsartikel (refereegranskat)abstract
- Cutaneous squamous cell carcinoma (cSCC) is a common skin cancer with metastatic potential. To reduce reoperations due to nonradical excision, there is a need to develop a technique for identification of tumor margins preoperatively. Photoacoustic (PA) imaging is a novel imaging technology that combines the strengths of laser optics and ultrasound. Our aim was to determine the spectral signature of cSCC using PA imaging and to use this signature to visualize tumor architecture and borders. Two-dimensional PA images of 33 cSCCs and surrounding healthy skin were acquired ex vivo, using 59 excitation wavelengths from 680 to 970 nm. The spectral response of the cSCCs was compared to healthy tissue, and the difference was found to be greatest at wavelengths in the range 765 to 960 nm (P <.05). Three-dimensional PA images were constructed from spectra obtained in the y-z plane using a linear stepper motor moving along the x-plane. Spectral unmixing was then performed which provided a clear three-dimensional view of the distribution of tumor masses and their borders.
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| 10. |
- Håkansson, Gisela, et al.
(författare)
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Hypoxia-inducible factor and vascular endothelial growth factor in the neuroretina and retinal blood vessels after retinal ischemia
- 2010
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Ingår i: Journal of Ocular Biology, Diseases, and Informatics. - : Springer Science and Business Media LLC. - 1936-8445. ; 3:1, s. 20-29
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Tidskriftsartikel (refereegranskat)abstract
- Retinal ischemia arises from circulatory failure. As the retinal blood vessels are key organs in circulatory failure, our aim was to study the retinal vasculature separately from the neuroretina to elucidate the role of hypoxia-inducible factor (HIF) 1α and 1β and vascular endothelial growth factor (VEGF) in retinal ischemia. Retinal ischemia was induced in porcine eyes by applying an intraocular pressure, followed by 12 h of reperfusion. HIF-1α mRNA expression was not affected by ischemia, while immunofluorescence staining was higher after ischemia in the neuroretina. HIF-1β immu-noreactivity and mRNA expression were unaffected. VEGF protein levels in the vitreous humor and VEGF staining in the neuroretina were more pronounced in eyes subjected to ischemia than in the sham eyes. VEGF may be activated downstream of HIF-1 and is known to stimulate retinal neovascularization, which causes sight-threatening complications. These results emphasize the need for pharmacological treatment to block the HIF and VEGF signaling pathways in retinal ischemia.
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