| 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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| 11. |
- Lindstedt Ingemansson, Sandra, et al.
(författare)
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A compare between myocardial topical negative pressure levels of-25 mmHg and-50 mmHg in a porcine model
- 2008
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Ingår i: BMC Cardiovascular Disorders. - : Springer Science and Business Media LLC. - 1471-2261. ; 8:14
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Tidskriftsartikel (refereegranskat)abstract
- Background: Topical negative pressure (TNP), widely used in wound therapy, is known to stimulate wound edge blood flow, granulation tissue formation, angiogenesis, and revascularization. We have previously shown that application of a TNP of -50 mmHg to the myocardium significantly increases microvascular blood flow in the underlying tissue. We have also shown that a myocardial TNP levels between -75 mmHg and -150 mmHg do not induce microvascular blood flow changes in the underlying myocardium. The present study was designed to elucidate the difference between -25 mmHg and -50 mmHg TNP on microvascular flow in normal and ischemic myocardium. Methods: Six pigs underwent median sternotomy. The microvascular blood flow in the myocardium was recorded before and after the application of TNP using laser Doppler flowmetry. Analyses were performed before left anterior descending artery (LAD) occlusion (normal myocardium), and after 20 minutes of LAD occlusion (ischemic myocardium). Results: A TNP of -25 mmHg significantly increased microvascular blood flow in both normal (from 263.3 +/- 62.8 PU before, to 380.0 +/- 80.6 PU after TNP application, *p = 0.03) and ischemic myocardium (from 58.8 +/- 17.7 PU before, to 85.8 +/- 20.9 PU after TNP application, *p = 0.04). A TNP of -50 mmHg also significantly increased microvascular blood flow in both normal (from 174.2 +/- 20.8 PU before, to 240.0 +/- 34.4 PU after TNP application, *p = 0.02) and ischemic myocardium (from 44.5 +/- 14.0 PU before, to 106.2 +/- 26.6 PU after TNP application, **p = 0.01). Conclusion: Topical negative pressure of -25 mmHg and -50 mmHg both induced a significant increase in microvascular blood flow in normal and in ischemic myocardium. The increase in microvascular blood flow was larger when using -25 mmHg on normal myocardium, and was larger when using -50 mmHg on ischemic myocardium; however these differences were not statistically significant.
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| 12. |
- Lindstedt Ingemansson, Sandra, et al.
(författare)
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Evaluation of continuous and intermittent myocardial topical negative pressure.
- 2008
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Ingår i: Journal of Cardiovascular Medicine. - 1558-2027. ; 9:8, s. 813-819
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Topical negative pressure, commonly used in wound therapy, has been shown to increase blood flow and stimulate angiogenesis in subcutaneous tissue and skeletal muscle. In wound therapy, intermittent negative pressure is often preferred to continuous negative pressure as tissue exposed to intermittent therapy shows twice as much granulation tissue formation than that exposed to continuous pressure after 2 weeks of therapy. The present study was designed to elucidate the differences in microvascular blood flow in the left anterior descending artery area between continuous and intermittent myocardial topical negative pressure of -50 mmHg. METHODS: Six pigs underwent median sternotomy. Laser Doppler probes were inserted horizontally into the heart muscle in the left anterior descending artery area at depths of approximately 5-6 mm. Measurements of microvascular blood flow were performed in normal myocardium and ischemic myocardium during 20 min of countinuous and intermittent topical negative pressure at -50 mmHg. RESULTS: Both continuous and intermittent topical negative pressure of -50 mmHg significantly increased microvascular blood flow in the underlying myocardium: from 56.2 +/- 13.1 perfusion units (PU) before to 132.8 +/- 7.4 PU during countinuous topical negative pressure application (P < 0.05) and from 75.8 +/- 12.1 PU before to 153.6 +/- 4.7 PU during intermittent topical negative pressure application (P < 0.05). CONCLUSION: No statistically significant difference was found between microvascular blood flow during 20 min of continuous and intermittent topical negative pressure at -50 mmHg in this porcine model.
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| 13. |
- Lindstedt Ingemansson, Sandra, et al.
(författare)
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Topical negative pressure effects on coronary blood flow in a sternal wound model.
- 2008
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Ingår i: International Wound Journal. - 1742-481X. ; 5:4, s. 503-509
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Tidskriftsartikel (refereegranskat)abstract
- Several studies have suggested that mediastinitis is a strong predictor for poor long-term survival after coronary artery bypass surgery (CABG). In those studies, several conventional wound-healing techniques were used. Previously, we have shown no difference in long-term survival between CABG patients with topical negative pressure (TNP)-treated mediastinitis and CABG patients without mediastinitis. The present study was designed to elucidate if TNP, applied over the myocardium, resulted in an increase of the total amount of coronary blood flow. Six pigs underwent median sternotomy. The coronary blood flow was measured, before and after the application of TNP (-50 mmHg), using coronary electromagnetic flow meter probes. Analyses were performed before left anterior descending artery (LAD) occlusion (normal myocardium) and after 20 minutes of LAD occlusion (ischaemic myocardium). Normal myocardium: 171.3 +/- 14.5 ml/minute before to 206.3 +/- 17.6 ml/minute after TNP application, P < 0.05. Ischaemic myocardium: 133.7 +/- 18.4 ml/minute before to 183.2 +/- 18.9 ml/minute after TNP application, P < 0.05. TNP of -50 mmHg applied over the LAD region induced a significant increase in the total coronary blood flow in both normal and ischaemic myocardium.
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| 14. |
- Malmsjö, Malin, et al.
(författare)
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The effects of variable, intermittent, and continuous negative pressure wound therapy, using foam or gauze, on wound contraction, granulation tissue formation, and ingrowth into the wound filler
- 2012
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Ingår i: Eplasty: Open Access Journal of Plastic and Reconstructive Surgery. - 1937-5719. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Negative pressure wound therapy (NPWT) is commonly used in the continuous mode. Intermittent pressure therapy (IPT) results in faster wound healing, but it often causes pain. Variable pressure therapy (VPT) has therefore been introduced to provide a smooth transition between 2 different pressure environments, thereby maintaining the negative pressure environment throughout the therapy. The aim of the present study was to examine the effects of IPT and VPT on granulation tissue formation.METHOD: A peripheral wound in a porcine model was treated for 72 hours with continuous NPWT (-80 mm Hg), IPT (0 to -80 mm Hg), or VPT (-10 to -80 mm Hg), using foam or gauze as wound filler. Wound contraction and force to remove the wound filler were measured. Biopsies from the wound bed were examined histologically for granulation tissue formation.RESULTS: Intermittent pressure therapy and VPT produced similar results. Wound contraction was more pronounced following IPT and VPT than continuous NPWT. Intermittent pressure therapy and VPT resulted in the formation of more granulation tissue than continuous NPWT. Leukocyte infiltration and tissue disorganization were more prominent after IPT and VPT than after continuous NPWT. Granulation tissue grew into foam but not into gauze, regardless of the mode of negative pressure application, and less force was needed to remove gauze than foam.CONCLUSIONS: Wound contraction and granulation tissue formation is more pronounced following IPT and VPT than continuous NPWT. Granulation tissue grows into foam but not into gauze. The choice of negative pressure mode and wound filler is crucial in clinical practice to optimize healing while minimizing pain.
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| 15. |
- Morén, Håkan, et al.
(författare)
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Angiography and mfERG show that blood supply to the pig retina may be both ipsilateral and contralateral.
- 2013
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Ingår i: Investigative Ophthalmology & Visual Science. - : Association for Research in Vision and Ophthalmology (ARVO). - 1552-5783. ; 54:9, s. 6112-6117
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: We recently presented a transfemoral endovascular coiling technique for inducing experimental retinal ischemia in pigs. Substantial variation was seen in the degree of ischemia. It was hypothesized that the blood supply to the retina may originate from both the ipsi- and contralateral ophthalmic arteries, and that there may be an interconnecting artery between the eyes. Methods: The external carotid system of ten pigs was catheterized using a fluoroscopy- monitored, transfemoral, endovascular approach. Vascular occlusion was achieved in the ophthalmic artery using coils. The effect of occlusion was examined using angiography and multifocal electroretinography (mfERG). Results: During angiography of the ophthalmic artery on one side, contrast filling was seen in the retinas on both sides, suggesting that the ophthalmic artery on one side may supply both retinas. A blood vessel connecting the eyes was visualized. mfERG recordings showed that the use of coiling to occlude the ophthalmic artery had greater ischemic effects in eyes that depended mainly on the ipsilateral ophthalmic artery for blood supply and smaller ischemic effect in retinas that received blood from both the ipsilateral and contralateral ophthalmic artery via the interconnecting vessel. Conclusions: The blood supply to the retina may originate from both the ipsi- and contralateral ophthalmic artery in the pig. There is an interindividual variability in the ischemic effect of occlusion depending on the architecture of the vasculature. These findings may be important in the development of new animal models of experimental retinal ischemia, since arterial occlusion in one eye may affect the blood supply to the contralateral eye.
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| 16. |
- Morén, Håkan, et al.
(författare)
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Endovascular Coiling of the Ophthalmic Artery in Pigs to Induce Retinal Ischemia
- 2011
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Ingår i: Investigative Ophthalmology & Visual Science. - : Association for Research in Vision and Ophthalmology (ARVO). - 1552-5783. ; 52:7, s. 4880-4885
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE. The authors recently showed that the retinal circulation can be accessed by transfemoral endovascular catheterization. The purpose of this study was to examine whether endovascular coiling can be used to induce different degrees of ischemic injury. The possibility of creating occlusions at different sites in the vasculature to cause retinal ischemia with different degrees of severity was investigated. METHODS. The ophthalmic artery was catheterized through the external carotid system using a fluoroscopy-monitored, transfemoral, endovascular approach in 12 pigs (mean weight, 70 kg). The effects were evaluated using angiography and multifocal electroretinography. RESULTS. Occlusion of arteries supplying the retina was established using endovascular coiling. Coiling in the proximal part of the ophthalmic artery caused no or little ischemia, presumably because of collateral blood supply. Coiling in the distal part of the ophthalmic artery, over the branching of the main ciliary artery, caused more severe retinal ischemia. Multifocal electroretinography recordings, which reflect retinal function in an area close to the visual streak, showed decreased amplitudes and increased implicit times after distal occlusion, but not after proximal occlusion of the ophthalmic artery. The responses were similar 1 hour and 72 hours after coiling, indicating that a permanent ischemic injury was established. CONCLUSIONS. The porcine ophthalmic artery can be occluded using an endovascular coiling technique. This provides an experimental animal model of retinal ischemia in which occlusion at different sites of the vasculature produces different degrees of severity of the ischemic damage. (Invest Ophthalmol Vis Sci. 2011;52:4880-4885) DOI:10.1167/iovs.11-7628
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| 17. |
- Morén, Håkan, et al.
(författare)
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Multifocal electroretinogram for functional evaluation of retinal injury following ischemia-reperfusion in pigs.
- 2010
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Ingår i: Graefe's Archive for Clinical and Experimental Ophthalmology. - : Springer Science and Business Media LLC. - 1435-702X .- 0721-832X. ; 248, s. 627-634
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Multifocal electroretinogram (mfERG) has the power to discriminate between localized functional losses and overall retinal changes when evaluating retinal injury. So far, full-field ERG has been the gold standard for examining retinal ischemia and the effects of different neuroprotectants in experimental conditions. The aim of the present study was to establish mfERG, with simultaneous fundus monitoring, for analyzing the localized functional response in the retina after ischemia-reperfusion in the porcine eye. METHODS: 70 kg pigs underwent pressure-induced retinal ischemia (1 hour) followed by reperfusion. mfERG recordings were obtained before and after ischemia, followed by 1 and 5 hours of reperfusion. Individual components of the summed mfERG responses were correlated to ischemia and the time of reperfusion. RESULTS: The visual streak area had significantly higher amplitudes than the optic nerve head and the area in between, suggesting that the mfERG monitors localized functional retinal responses. The mfERG recordings were altered following ischemia-reperfusion. In one group of animals, there was a complete flattening of the mfERG waveforms, indicating complete ischemic injury. In the other group of animals, ischemia-reperfusion altered the mfERG such that the implicit time was increased (20.82 +/- 0.18 before ischemia and 21.57 +/- 0.21 after ischemia and 1 hour of reperfusion, in the visual streak area, p < 0.05) and the amplitude was decreased (13.16 +/- 2.3 before ischemia and 11.47 +/- 0.88 after ischemia and 1 hour of reperfusion, in the visual streak area, p < 0.001), suggesting partial ischemic injury. CONCLUSIONS: In conclusion, the porcine model of pressure-induced retinal ischemia-reperfusion results in mfERG changes, typical for retinal ischemia. mfERG may be a useful tool for evaluating and monitoring localized cone dysfunction after an ischemic injury.
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| 18. |
- Morén, Håkan, et al.
(författare)
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The porcine retinal vasculature can be accessed using an endovascular approach, a new experimental model for retinal ischemia.
- 2009
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Ingår i: Investigative Ophthalmology & Visual Science. - : Association for Research in Vision and Ophthalmology (ARVO). - 1552-5783. ; 50:11, s. 5504-5510
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Tidskriftsartikel (refereegranskat)abstract
- Purpose. The aim was to examine if the retinal circulation in the pig can be accessed using interventional neuroradiology and to explore the possibility to create occlusions that result in experimental retinal ischemia. Methods. Six experiments were performed using 100 kg pigs. The external carotid system was catheterizised using fluoroscopy monitored, transfemoral, endovascular approach. Transient and permanent vascular occlusions were performed using an angioplasty balloon catheter or a liquid embolic agent that was administered via an injection-catheter. Results. A technique for transfemoral catheterization of arteries supplying the retina was established. The ophthalmic artery was demonstrated to give rise to the main ciliary artery, from which the retinal artery branched as a single or several arteries. A balloon-catheter could be introduced into the ophthalmic artery, but not into the main ciliary artery. An injection-catheter could, in all experiments, be introduced into the main ciliary artery and, in some experiments, into the retinal artery. Occlusion of the ophthalmic artery, over the branching of the main ciliary artery, caused incomplete ischemia, presumably due to collaterals feeding the distal parts of the vasculature. mfERG recordings showed decreased amplitudes and increased implicit times, indicating retinal ischemia. Occlusion of the ciliary and retinal arteries caused complete ischemia, as shown by complete flattening of the mfERG recordings and, by indirect ophthalmoscopy, blanching of the retinal arteries and a pale retina Conclusions. We prove for the first time that the ophthalmic and retinal artery can be catheterizised using a transfemoral endovascular approach. This technique may be useful to produce clear-cut experimental retinal ischemia.
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| 19. |
- Nilsson, David, et al.
(författare)
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Up-regulation of endothelin type B receptors in the human internal mammary artery in culture is dependent on protein kinase C and mitogen-activated kinase signaling pathways.
- 2008
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Ingår i: BMC Cardiovascular Disorders. - : Springer Science and Business Media LLC. - 1471-2261. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Up-regulation of vascular endothelin type B (ETB) receptors is implicated in the pathogenesis of cardiovascular disease. Culture of intact arteries has been shown to induce similar receptor alterations and has therefore been suggested as a suitable method for, ex vivo, in detail delineation of the regulation of endothelin receptors. We hypothesize that mitogen-activated kinases (MAPK) and protein kinase C (PKC) are involved in the regulation of endothelin ETB receptors in human internal mammary arteries. METHODS: Human internal mammary arteries were obtained during coronary artery bypass graft surgery and were studied before and after 24 hours of organ culture, using in vitro pharmacology, real time PCR and Western blot techniques. Sarafotoxin 6c and endothelin-1 were used to examine the endothelin ETA and ETB receptor effects, respectively. The involvement of PKC and MAPK in the endothelin receptor regulation was examined by culture in the presence of antagonists. RESULTS: The endohtelin-1-induced contraction (after endothelin ETB receptor desensitization) and the endothelin ETA receptor mRNA expression levels were not altered by culture. The sarafotoxin 6c contraction, endothelin ETB receptor protein and mRNA expression levels were increased after organ culture. This increase was antagonized by; (1) PKC inhibitors (10 microM bisindolylmaleimide I and 10 microM Ro-32-0432), and (2) inhibitors of the p38, extracellular signal related kinases 1 and 2 (ERK1/2) and C-jun terminal kinase (JNK) MAPK pathways (10 microM SB203580, 10 microM PD98059 and 10 microM SP600125, respectively). CONCLUSION: In conclusion, PKC and MAPK seem to be involved in the up-regulation of endothelin ETB receptor expression in human internal mammary arteries. Inhibiting these intracellular signal transduction pathways may provide a future therapeutic target for hindering the development of vascular endothelin ETB receptor changes in cardiovascular disease.
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| 20. |
- Sheikh, Rafi, et al.
(författare)
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Hypoperfusion following the injection of epinephrine in human forearm skin can be measured by RGB analysis but not with laser speckle contrast imaging
- 2019
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Ingår i: Microvascular Research. - : Elsevier BV. - 0026-2862. ; 121, s. 7-13
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundThe time taken for epinephrine to achieve its optimal effect during local anesthesia has recently become the subject of debate. The time from injection to commencement of surgery is traditionally quoted to be 7 to 10 min, while recent reports claim that it may take 30 min to achieve maximum hypoperfusion, which would prolong the time required for surgical procedures. The discrepancy may be related to difficulties associated with the techniques used to measure blood perfusion. The aim of this study was to test two methods of determining the time to maximum hypoperfusion.MethodsLaser speckle contrast imaging (LSCI) and red, green, blue (RGB) analysis of images obtained with a commercial digital camera, were used to monitor the effect of infiltration with commonly used local anesthetic preparations: lidocaine (20 mg/ml) + epinephrine (12.5 μg/ml), lidocaine (10 mg/ml) + epinephrine (5 μg/ml), and lidocaine (20 mg/ml) alone, in healthy subjects.ResultsLSCI showed a paradoxical increase in signal after the injection of local anesthetics containing epinephrine, probably due to a change in the laser penetration depth resulting from blanching of the skin. However, RGB analysis of digital photographs gave more reliable results, showing skin blanching that corresponded to the expected effect of epinephrine in local anesthetics. The time to maximum effect was found to be 7 (range 5–10) minutes for 12.5 μg/ml epinephrine, and 9 (range 7–13) minutes for 5 μg/ml epinephrine in lidocaine.ConclusionsRGB analysis of digital images proved to be a valid technique for monitoring the effect of local anesthetics with epinephrine in human skin. The technique requires only a commercial digital camera and constitutes a cheap, simple method. The optimal delay between epinephrine injection and incision, to minimize bleeding, was found to be 7 to 9 min, which is in good agreement with common surgical practice.
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| 21. |
- Sheikh, Rafi, et al.
(författare)
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Photoacoustic imaging for non-invasive examination of the healthy temporal artery - systematic evaluation of visual function in healthy subjects
- 2021
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Ingår i: Acta Ophthalmologica. - : Wiley. - 1755-3768 .- 1755-375X. ; 99:2, s. 227-231
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Photoacoustic (PA) imaging has the potential to become a non-invasive diagnostic tool for giant cell arteritis, as shown in pilot experiments on seven patients undergoing surgery. Here, we present a detailed evaluation of the safety regarding visual function and patient tolerability in healthy subjects, and define the spectral signature in the healthy temporal artery.METHODS: Photoacoustic scanning of the temporal artery was performed in 12 healthy subjects using 59 wavelengths (from 680 nm to 970 nm). Visual function was tested before and after the examination. The subjects' experience of the examination was rated on a 0-100 VAS scale. Two- and three-dimensional PA images were generated from the spectra obtained from the artery.RESULTS: Photoacoustic imaging did not affect the best corrected visual acuity, colour vision (tested with Sahlgren's Saturation Test or the Ishihara colour vision test) or the visual field. The level of discomfort was low, and only little heat and light sensation were reported. The spectral signature of the artery wall could be clearly differentiated from those of the subcutaneous tissue and skin. Spectral unmixing provided visualization of the chromophore distribution and overall architecture of the artery.CONCLUSIONS: Photoacoustic imaging of the temporal artery is well tolerated and can be performed without any risk to visual function, including the function of the retina and the optic nerve. The spectral signature of the temporal artery is specific, which is promising for future method development.
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| 22. |
- Stridh, Magne, et al.
(författare)
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Functional and molecular 3D mapping of angiosarcoma tumor using non-invasive laser speckle, hyperspectral, and photoacoustic imaging
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Ingår i: Orbit (London). - 0167-6830.
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The gold standard for skin cancer diagnosis is surgical excisional biopsy and histopathological examination. Several non-invasive diagnostic techniques exist, although they have not yet translated into clinical use. This is a proof-of-concept study to assess the possibility of imaging an angiosarcoma in the periocular area.METHODS: We use laser speckle, hyperspectral, and photoacoustic imaging to monitor blood perfusion and oxygen saturation, as well as the molecular composition of the tissue. The information obtained from each imaging modality was combined in order to yield a more comprehensive picture of the function, as well as molecular composition of a rapidly growing cutaneous angiosarcoma in the periocular area.RESULTS: We found an increase in perfusion coupled with a reduction in oxygen saturation in the angiosarcoma. We could also extract the molecular composition of the angiosarcoma at a depth, depicting both the oxygen saturation and highlighting the presence of connective tissue via collagen.CONCLUSIONS: We demonstrate the different physiological parameters that can be obtained with the different techniques and how these can be combined to provide detailed 3D maps of the functional and molecular properties of tumors useful in preoperative assessment.
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| 23. |
- Stridh, Magne Tordengren, et al.
(författare)
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Photoacoustic imaging of periorbital skin cancer ex vivo: unique spectral signatures of malignant melanoma, basal, and squamous cell carcinoma : Biomedical Optics Express
- 2022
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Ingår i: Biomed. Opt. Express. - 2156-7085. ; 13:1, s. 410-425
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Tidskriftsartikel (refereegranskat)abstract
- Radical excision of periorbital skin tumors is difficult without sacrificing excessive healthy tissue. Photoacoustic (PA) imaging is an emerging non-invasive biomedical imaging modality that has potential for intraoperative micrographic control of surgical margins. This is the first study to assess the feasibility of PA imaging for the detection of periocular skin cancer. Eleven patients underwent surgical excision of periocular skin cancer, one of which was a malignant melanoma (MM), eight were basal cell carcinomas (BCCs), and two squamous cell carcinomas (SCCs). Six tumors were located in the eyelid, and five in periocular skin. The excised samples, as well as healthy eyelid samples, were scanned with PA imaging postoperatively, using 59 wavelengths in the range 680–970 nm, to generate 3D multispectral images. Spectral unmixing was performed using endmember spectra for oxygenated and deoxygenated Hb, melanin, and collagen, to identify the chromophore composition of tumors and healthy eyelid tissue. After PA scanning, the tumor samples were examined histopathologically using standard hematoxylin and eosin staining. The PA spectra of healthy eyelid tissue were dominated by melanin in the skin, oxygenated and deoxygenated hemoglobin in the orbicularis oculi muscle, and collagen in the tarsal plate. Multiwavelength 3D scanning provided spectral information on the three tumor types. The spectrum from the MM was primarily reconstructed by the endmember melanin, while the SCCs showed contributions primarily from melanin, but also HbR and collagen. BCCs showed contributions from all four endmembers with a predominance of HbO2 and HbR. PA imaging may be used to distinguish different kinds of periocular skin tumors, paving the way for future intraoperative micrographic control.
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