| 1. |
- Khodaverdi, Azin, et al.
(författare)
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The feasibility of using center frequency spectra in photoacoustic imaging for tissue characterization
- 2023
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Ingår i: IUS 2023 - IEEE International Ultrasonics Symposium, Proceedings. - 1948-5727 .- 1948-5719. - 9798350346459
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Konferensbidrag (refereegranskat)abstract
- In photoacoustic imaging, the amplitude of the photoacoustic signal is used for mapping the spatial distribution of a chromophore in the body and few studies have focused on the potential of using frequency content of the photoacoustic data. This study investigates the feasibility of using the photoacoustic center frequency spectrum in differentiating microspheres of various sizes and colors in phantoms. The microspheres with colors of green and blue, and the same size showed different center frequency spectrum shapes while keeping the offset (mean frequency) approximately the same. In addition, smaller microspheres showed higher center frequency offset, while larger microspheres showed smaller offset, suggesting the potential to use the center frequency spectrum for differentiating chromophores of various optical properties in the body.
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| 2. |
- Lindstedt Ingemansson, Sandra, et al.
(författare)
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Myocardial topical negative pressure increases blood flow in hypothermic, ischemic myocardium.
- 2008
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Ingår i: Scandinavian Cardiovascular Journal. - : Informa UK Limited. - 1651-2006 .- 1401-7431. ; 42, s. 345-353
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Tidskriftsartikel (refereegranskat)abstract
- Objectives. Hypothermia protects the myocardium from oxidative injury during ischemic stress and reperfusion. We have previously shown that topical negative pressure (TNP) of -50 mmHg significantly increases microvascular blood flow in the underlying myocardium in normal, ischemic, and reperfused porcine myocardium. The present study was designed to elucidate the effect of TNP between -50 mmHg and -150 mmHg on microvascular blood flow in ischemic myocardium during hypothermia. Design. The microvascular blood flow in the myocardium was recorded, in seven pigs, using laser Doppler velocimetry. Analyses were performed in the epicardium and in the myocardium, after 40 minutes of occlusion of the LAD followed by cooling to 31 degrees C. Results. A TNP of -50 mmHg applied to the epicardium, from 23.3+/-3.8 PU to 104.2+/-31.3 PU (*p <0.05), and in the myocardium, from 35.0+/-7.2 PU to 74.2+/-21.8 PU (*p <0.05). Conclusions. Only a TNP level of -50 mmHg significantly increased the microvascular blood flow in both the epicardium and in the myocardium during hypothermia.
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| 3. |
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| 4. |
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| 5. |
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| 6. |
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| 7. |
- Alm, Rikard, et al.
(författare)
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Organ culture: a new model for vascular endothelium dysfunction.
- 2002
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Ingår i: BMC Cardiovascular Disorders. - 1471-2261. ; 2:1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Endothelium dysfunction is believed to play a role in the development of cardiovascular disease. The aim of the present study was to evaluate the suitability of organ culture as a model for endothelium dysfunction. METHODS: The isometric tension was recorded in isolated segments of the rat mesenteric artery branch, before and after organ culture for 20 h. Vasodilatation was expressed as % of preconstriction with U46619. The acetylcholine (ACh) induced nitric oxide (NO) mediated dilatation was studied in the presence of 10 &mgr;M indomethacin, 50 nM charybdotoxin and 1 &mgr;M apamin. Endothelium-derived hyperpolarising factor (EDHF) was studied in the presence of 0.1 mM L-NOARG and indomethacin. Prostaglandins were studied in the presence of L-NOARG, charybdotoxin and apamin. RESULTS: The ACh-induced NO and prostaglandin-mediated dilatations decreased significantly during organ culture (NO: 84% in control and 36% in cultured; prostaglandins: 48% in control and 16% in cultured). Notably, the total ACh-dilatation was not changed. This might be explained by the finding that EDHF alone stimulated a full dilatation even after organ culture (83% in control and 80% in cultured). EDHF may thereby compensate for the loss in NO and prostaglandin-mediated dilatation. Dilatations induced by forskolin or sodium nitroprusside did not change after organ culture, indicating intact smooth muscle cell function. CONCLUSIONS: Organ culture induces a loss in NO and prostaglandin-mediated dilatation, which is compensated for by EDHF. This shift in mediator profile resembles that in endothelium dysfunction. Organ culture provides an easily accessible model where the molecular changes that take place, when endothelium dysfunction is developed, can be examined over time.
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| 8. |
- Andersson, Emil, et al.
(författare)
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Facilitating clinically relevant skin tumor diagnostics with spectroscopy-driven machine learning
- 2024
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Ingår i: iScience. - 2589-0042. ; 27:5
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Tidskriftsartikel (refereegranskat)abstract
- In the dawning era of artificial intelligence (AI), health care stands to undergo a significant transformation with the increasing digitalization of patient data. Digital imaging, in particular, will serve as an important platform for AI to aid decision making and diagnostics. A growing number of studies demonstrate the potential of automatic pre-surgical skin tumor delineation, which could have tremendous impact on clinical practice. However, current methods rely on having ground truth images in which tumor borders are already identified, which is not clinically possible. We report a novel approach where hyperspectral images provide spectra from small regions representing healthy tissue and tumor, which are used to generate prediction maps using artificial neural networks (ANNs), after which a segmentation algorithm automatically identifies the tumor borders. This circumvents the need for ground truth images, since an ANN model is trained with data from each individual patient, representing a more clinically relevant approach.
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| 9. |
- Andreasson, Jesper, et al.
(författare)
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Exhaled phospholipid transfer protein and hepatocyte growth factor receptor in lung adenocarcinoma
- 2022
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Ingår i: Respiratory Research. - : Springer Science and Business Media LLC. - 1465-9921 .- 1465-993X. ; 23:1, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Screening decreases mortality among lung cancer patients but is not widely implemented, thus there is an unmet need for an easily accessible non-invasive method to enable early diagnosis. Particles in exhaled air offer a promising such diagnostic tool. We investigated the validity of a particles in exhaled air device (PExA) to measure the particle flow rate (PFR) and collect exhaled breath particles (EBP) to diagnose primary lung adenocarcinoma (LUAD).METHODS: Seventeen patients listed for resection of LUAD stages IA-IIIA and 18 non-cancer surgical control patients were enrolled. EBP were collected before and after surgery for LUAD, and once for controls. Proteomic analysis was carried out using a proximity extension assay technology. Results were validated in both plasma from the same cohort and with microarray data from healthy lung tissue and LUAD tissue in the GSE10072 dataset.RESULTS: Of the 92 proteins analyzed, levels of five proteins in EBP were significantly higher in the LUAD patients compared to controls. Levels of phospholipid transfer protein (PLTP) and hepatocyte growth factor receptor (MET) decreased in LUAD patients after surgery compared to control patients. PFR was significantly higher in the LUAD cohort at all timepoints compared to the control group. MET in plasma correlated significantly with MET in EBP.CONCLUSION: Collection of EBP and measuring of PFR has never been performed in patients with LUAD. In the present study PFR alone could distinguish between LUAD and patients without LUAD. PLTP and MET were identified as potential biomarkers to evaluate successful tumor excision.
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| 10. |
- Anesater, Erik, et al.
(författare)
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A Rigid Disc for Protection of Exposed Blood Vessels During Negative Pressure Wound Therapy
- 2013
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Ingår i: Surgical Innovation. - : SAGE Publications. - 1553-3506 .- 1553-3514. ; 20:1, s. 74-80
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Tidskriftsartikel (refereegranskat)abstract
- Background. There are increasing reports of serious complications and deaths associated with negative pressure wound therapy (NPWT). Bleeding may occur when NPWT is applied to a wound with exposed blood vessels. Inserting a rigid disc in the wound may protect these structures. The authors examined the effects of rigid discs on wound bed tissue pressure and blood flow through a large blood vessel in the wound bed during NPWT. Methods. Wounds were created over the femoral artery in the groin of 8 pigs. Rigid discs were inserted. Wound bed pressures and arterial blood flow were measured during NPWT. Results. Pressure transduction to the wound bed was similar for control wounds and wounds with discs. Blood flow through the femoral artery decreased in control wounds. When a disc was inserted, the blood flow was restored. Conclusions. NPWT causes hypoperfusion in the wound bed tissue, presumably as a result of mechanical deformation. The insertion of a rigid barrier alleviates this effect and restores blood flow.
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| 11. |
- Anesäter, Erik, et al.
(författare)
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The influence of different sizes and types of wound fillers on wound contraction and tissue pressure during negative pressure wound therapy.
- 2011
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Ingår i: International Wound Journal. - 1742-481X. ; 8, s. 336-342
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Tidskriftsartikel (refereegranskat)abstract
- Negative pressure wound therapy (NPWT) contracts the wound and alters the pressure in the tissue of the wound edge, which accelerates wound healing. The aim of this study was to examine the effect of the type (foam or gauze) and size (small or large) of wound filler for NPWT on wound contraction and tissue pressure. Negative pressures between -20 and -160 mmHg were applied to a peripheral porcine wound (n = 8). The pressure in the wound edge tissue was measured at distances of 0·1, 0·5, 1·0 and 2·0 cm from the wound edge and the wound diameter was determined. At 0·1 cm from the wound edge, the tissue pressure decreased when NPWT was applied, whereas at 0·5 cm it increased. Tissue pressure was not affected at 1·0 or 2·0 cm from the wound edge. The tissue pressure, at 0·5 cm from the wound edge, was greater when using a small foam than when using than a large foam. Wound contraction was greater when using a small foam than when using a large foam during NPWT. Gauze resulted in an intermediate wound contraction that was not affected by the size of the gauze filler. The use of a small foam to fill the wound causes considerable wound contraction and may thus be used when maximal mechanical stress and granulation tissue formation are desirable. Gauze or large amounts of foam result in less wound contraction which may be beneficial, for example when NPWT causes pain to the patient.
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| 12. |
- Anesäter, Erik, et al.
(författare)
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The influence on wound contraction and fluid evacuation of a rigid disc inserted to protect exposed organs during negative pressure wound therapy.
- 2011
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Ingår i: International Wound Journal. - 1742-481X. ; 8, s. 393-399
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Tidskriftsartikel (refereegranskat)abstract
- The use of a rigid disc as a barrier between the wound bed and the wound filler during negative pressure wound therapy (NPWT) has been suggested to prevent damage to exposed organs. However, it is important to determine that the effects of NPWT, such as wound contraction and fluid removal, are maintained during treatment despite the use of a barrier. This study was performed to examine the effect of NPWT on wound contraction and fluid evacuation in the presence of a rigid disc. Peripheral wounds were created on the backs of eight pigs. The wounds were filled with foam, and rigid discs of different designs were inserted between the wound bed and the foam. Wound contraction and fluid evacuation were measured after application of continuous NPWT at -80 mmHg. Wound contraction was similar in the presence and the absence of a rigid disc (84 ± 4% and 83 ± 3%, respectively, compared with baseline). Furthermore, the rigid disc did not affect wound fluid removal compared with ordinary NPWT (e.g. after 120 seconds, 71 ± 4 ml was removed in the presence and 73 ± 3 ml was removed in the absence of a disc). This study shows that a rigid barrier may be placed under the wound filler to protect exposed structures during NPWT without affecting wound contraction and fluid removal, which are two crucial features of NPWT.
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| 13. |
- Anesäter, Erik, et al.
(författare)
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The use of a rigid disc to protect exposed structures in wounds treated with negative pressure wound therapy: Effects on wound bed pressure and microvascular blood flow.
- 2012
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Ingår i: Wound Repair and Regeneration. - 1524-475X. ; 20:4, s. 611-616
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Tidskriftsartikel (refereegranskat)abstract
- There are increasing reports of deaths and serious complications associated with the use of negative pressure wound therapy (NPWT). Bleeding may occur in patients when NPWT is applied to a wound with exposed blood vessels or vascular grafts, possibly due to mechanical deformation and hypoperfusion of the vessel walls. Recent evidence suggests that using a rigid barrier disc to protect underlying tissue can prevent this mechanical deformation. The aim of this study was to examine the effect of rigid discs on the tissue exposed to negative pressure with regard to tissue pressure and microvascular blood flow. Peripheral wounds were created on the backs of eight pigs. The pressure and microvascular blood flow in the wound bed were measured when NPWT was applied. The wound was filled with foam, and rigid discs of different designs were inserted between the wound bed and the foam. The discs were created with or without channels (to accommodate exposed sensitive structures such as blood vessels and nerves), perforations, or a porous dressing that covered the underside of the discs (to facilitate pressure transduction and fluid evacuation). When comparing the results for pressure transduction to the wound bed, no significant differences were found using different discs covered with dressing, whereas pressure transduction was lower with bare discs. Microvascular blood flow in the wound bed decreased by 49 ± 7% when NPWT was applied to control wounds. The reduction in blood flow was less in the presence of a protective disc (e.g., -6 ± 5% for a dressing-covered, perforated disc, p = 0.006). In conclusion, NPWT causes hypoperfusion of superficial tissue in the wound bed. The insertion of a rigid barrier counteracts this effect. The placement of a rigid disc over exposed blood vessels or nerves may protect these structures from rupture and damage.
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| 14. |
- Ansson, Cu, et al.
(författare)
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Blood perfusion in Hewes tarsoconjunctival flaps in pigs measured by laser speckle contrast imaging
- 2018
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Ingår i: JPRAS Open. - : Elsevier BV. - 2352-5878. ; 18, s. 98-103
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundHewes flap is a tarsoconjunctival eyelid flap, based at the lateral canthal tendon, and rotated and stretched to repair lateral defects in the lower eyelid commonly following tumor surgery. The aim of the present study was to monitor perfusion in a Hewes flap during reconstruction, which to the best of our knowledge, has not previously been done.MethodsA Hewes tarsoconjunctival eyelid flap was raised and the effects on blood perfusion of rotating the flaps by 90° and 180°, stretching the flaps with a force of 5 or 10 N, and repeated diathermic coagulation was monitored with laser speckle contrast imaging.ResultsRotating the flaps by 90° did not significantly affect perfusion, while further rotation to 180° reduced blood perfusion to 75% of the baseline value. When the tarsoconjunctival flaps were both rotated 90° and stretched with 5 N, the perfusion was reduced even further, to 63%. A further reduction in perfusion, to 36%, was seen when the higher force of 10 N was applied. Diathermy decreased blood perfusion to 56% after being applied once. Successive applications led to further decreases: 43%, 31%, and 15%, after the second, third and fourth applications.ConclusionsPerfusion in Hewes tarsoconjunctival flaps is affected by both rotation and stretching, but some perfusion is maintained despite these manipulations. Diathermy, however, has detrimental effects and should be avoided.
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| 15. |
- Ansson, Cu Dybelius, et al.
(författare)
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Perfusion in Upper Eyelid Flaps : Effects of Rotation and Stretching Measured With Laser Speckle Contrast Imaging in Patients
- 2020
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Ingår i: Ophthalmic Plastic and Reconstructive Surgery. - 1537-2677. ; 36:5, s. 481-484
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The aim of this study was to investigate how the blood perfusion in human upper eyelid skin flaps is affected by the length of the flap and the degree of stretching and rotation of the flap.METHODS: Twenty-nine upper eyelids were dissected as part of a blepharoplastic procedure in patients. The 1-cm wide proximal end of the flap remains attached, to mimic a random pattern skin flap (hereafter called a "skin flap"). Blood perfusion was measured with laser speckle contrast imaging before and after the flap was stretched with forces of 0.5, 1, and 2 N. The flap was then rotated 90°, and the same tensions were applied.RESULTS: Blood perfusion decreased gradually from the base to the tip of the flap. The flap was only well perfused in the proximal 1 cm (60% at 0.5 cm and 37% at 1.0 cm) and was minimally perfused beyond 2 cm (22% at 2.0 cm). Stretching the nonrotated flaps affected perfusion slightly (decreased to 43% at 0.5 cm). Simply rotating the flaps by 90° had no significant effect on the perfusion. The combination of rotation (90°) and stretching reduced the perfusion to 22% at 2 N, when measured 0.5 cm from the base.CONCLUSIONS: Blood perfusion in upper eyelid skin flaps decreases rapidly with distance from the base of the flap. Rotating and stretching the skin flap reduces blood perfusion even further, leading to minimal perfusion in this kind of flap at distances greater than 1.5 cm from the base.
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| 16. |
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| 17. |
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| 18. |
- Berggren, Johanna, et al.
(författare)
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Reperfusion of Free Full-Thickness Skin Grafts in Periocular Reconstructive Surgery Monitored Using Laser Speckle Contrast Imaging
- 2021
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Ingår i: Ophthalmic Plastic and Reconstructive Surgery. - 1537-2677. ; 37:4, s. 324-328
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Free skin grafts are frequently used in reconstructive surgery. However, little is known about the course of reperfusion due to the previous lack of reliable perfusion monitoring techniques. The aim of this study was to use state-of-the-art laser speckle contrast imaging to monitor free skin grafts in the periocular area.METHODS: Seven patients needing surgery due to tumor removal or cicatricial ectropion in the periocular region underwent reconstructive surgery using free skin grafts from either the contralateral upper eyelid or the upper inner arm. The free skin grafts measured 10-30 mm horizontally and 9-30 mm vertically. Blood perfusion was monitored using laser speckle contrast imaging immediately postoperatively (0 weeks) and at follow-up after 1, 3, and 7 weeks.RESULTS: All grafts were reperfused gradually during healing, the median value being 46% in the central part of the graft after 1 week and 79% after 3 weeks. The grafts were completely reperfused after 7 weeks. No difference was observed in the rate of reperfusion between the center and periphery of the grafts (p = not significant). The cosmetic and functional outcome was excellent in all but 1 patient, who developed ectropion that had to be surgically corrected.CONCLUSIONS: Skin grafts in the periorbital area are fully reperfused after 7 weeks. The periocular area is known to be well-vascularized and thus forgiving to reconstructive surgery. Future investigations of the reperfusion of free skin grafts in other parts of the body or in higher-risk populations should be carried out.
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| 19. |
- Berggren, Johanna, et al.
(författare)
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Revascularization After H-plasty Reconstructive Surgery in the Periorbital Region Monitored With Laser Speckle Contrast Imaging
- 2021
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Ingår i: Ophthalmic Plastic and Reconstructive Surgery. - 1537-2677. ; 37:3, s. 269-273
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: H-plasty reconstructive surgery is commonly used to close defects after tumor excision in the periorbital region. Revascularization of the bipedicle skin flaps is essential for healing. However, it has not previously been possible to study this revascularization in humans due to the lack of noninvasive perfusion monitoring techniques. The aim was to monitor perfusion in H-plasty flaps during surgery and during postoperative follow-up, using laser speckle contrast imaging.METHOD: H-plasty, i.e., bipedicle random advancement skin flaps, was used for reconstruction of the eyelids after tumor removal in 7 patients. The median length and width of the skin flaps were 13 mm (range, 8-20 mm) and 10 mm (range, 5-11 mm), respectively. Blood perfusion was measured using laser speckle contrast imaging during surgery and at follow up 1, 3, and 6 weeks postoperatively, to monitor revascularization.RESULTS: Immediately postoperatively, the perfusion in the distal end of the flaps had fallen to 54% (95% CI, 38%-67%). The perfusion then quickly increased during the healing process, being 104% (86%-124%) after 1 week, 115% (94%-129%) after 3 weeks, and 112% (96%-137%) after 6 weeks. There was no clinically observable ischemia or tissue necrosis.CONCLUSIONS: Revascularization of the H-plasty procedure flaps occurs quickly, within a week postoperatively, presumably due to the existing vascular network of the flap pedicle, and was not dependent on significant angiogenesis. This perfusion study confirms the general opinion that H-plasty is a good reconstructive technique, especially in the periorbital region with its rich vascular supply.
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| 20. |
- Berggren, Johanna, et al.
(författare)
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Revascularization of Free Skin Grafts Overlying Modified Hughes Tarsoconjunctival Flaps Monitored Using Laser-Based Techniques
- 2019
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Ingår i: Ophthalmic Plastic and Reconstructive Surgery. - 1537-2677. ; 35:4, s. 378-382
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: It has recently been shown that the flap pedicle does not supply blood to a tarsoconjunctival graft in the modified Hughes procedure in patients. This raises questions concerning the rate of revascularization of the free skin graft commonly used to reconstruct the anterior lamella. The aim of this study was, thus, to monitor the course of revascularization in free skin grafts overlying modified Hughes tarsoconjunctival flaps, using laser-based techniques.Methods: Free skin grafts from the upper eyelid or upper arm in 9 patients were used to cover a tarsoconjunctival flap according to the modified Hughes procedure. Blood perfusion was monitored using laser speckle contrast imaging, and vascular reactivity was studied with laser Doppler velocimetry after heating the tissue to 44°C. Measurements were made at the time of surgery (baseline) and at 1, 3, 8, and 16 weeks postoperatively.Results: The gradual increase in perfusion of the free skin grafts during the healing process indicates revascularization. A slight increase in perfusion was seen already after 1 week. Perfusion reached 50% of the baseline after 3 weeks, and complete restoration of perfusion was seen after 8 weeks. The vascular function monitored with heat-induced hyperemia increased in a similar fashion.Conclusions: Full-thickness skin grafts revascularize within 3 to 8 weeks, despite overlying a tarsoconjunctival flap, which has recently been reported to be avascular. This provides further evidence that it should be possible to repair large eyelid defects using free full-thickness eyelid grafts.
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| 21. |
- Berggren, Johanna V, et al.
(författare)
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Blood Perfusion of Human Upper Eyelid Skin Flaps Is Better in Myocutaneous than in Cutaneous Flaps
- 2022
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Ingår i: Ophthalmic Plastic and Reconstructive Surgery. - 1537-2677. ; 38:2, s. 166-169
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The aim of this study was to monitor blood perfusion in human upper eyelid skin flaps and examine how the perfusion is affected by the thickness of the flap.METHODS: Twenty upper eyelids were dissected as part of a blepharoplasty procedure in patients. The medial end of the blepharoplasty flap remained attached to mimic a flap design often used in reconstruction in the periocular area, a myocutaneous flap in which the blood supply follows the fibers of the orbicularis muscle and is thus parallel to the long axis of the flap. The muscle was thereafter dissected from the flap to create a cutaneous flap. Blood perfusion in the 2 types of flaps was compared using laser speckle contrast imaging.RESULTS: Blood perfusion decreased gradually from the base to the tip of all the flaps. Perfusion was significantly higher in the myocutaneous flaps than in the cutaneous flaps (p < 0.0004): 69% in the myocutaneous flaps and 43% in the cutaneous flaps, measured 5 mm from the base. Blood perfusion was preserved to a greater extent distally in the myocutaneous flaps (minimum value seen at 25 mm) than in the cutaneous flaps (minimum seen at 11 mm).CONCLUSIONS: Blood perfusion was better preserved in myocutaneous flaps, including both skin and the orbicularis oculi muscle, than in cutaneous flaps. This may be of clinical interest in patients with poor microcirculation in which a long flap is required for reconstructive surgery.
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| 22. |
- Berggren, Johanna V, et al.
(författare)
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Laser Speckle Contrast Imaging of a Rotational Full-Thickness Lower Eyelid Flap Shows Satisfactory Blood Perfusion
- 2021
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Ingår i: Ophthalmic Plastic and Reconstructive Surgery. - 1537-2677. ; 37:4, s. 139-141
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Tidskriftsartikel (refereegranskat)abstract
- Full-thickness eyelid flaps from the lower eyelid are frequently used to repair larger upper eyelid defects. Perfusion monitoring has recently been implemented in several reconstructive surgical procedures, however, perfusion monitoring of a rotational eyelid flap has not yet been described. The authors' employed laser speckle contrast imaging to monitor blood perfusion in a rotational flap from the lower eyelid, used to cover a large tumor defect in the upper eyelid. Perfusion in the flap decreased by only 50% during surgery and was almost completely restored 5 weeks later at flap division (91%). The excellent surgical outcome in the present case is deemed to be the result of satisfactory blood perfusion of the flap.
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| 23. |
- Berggren, Johanna V, et al.
(författare)
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Laser Speckle Contrast Imaging of the Blood Perfusion in Glabellar Flaps Used to Repair Medial Canthal Defects
- 2022
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Ingår i: Ophthalmic Plastic and Reconstructive Surgery. - 1537-2677. ; 38:3, s. 274-279
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The glabellar flap is a common technique for surgical repair after tumor excision in the medial canthal area. However, the outcome may be affected by partial flap necrosis. Little is known about the impact of surgery on blood perfusion and the postoperative course of reperfusion due to the absence of reliable and noninvasive perfusion monitoring techniques. The aim of this study was to use a modern imaging technique to assess blood perfusion in glabellar flaps.METHODS: Glabellar flaps were used to repair medial canthal defects following tumor excision in 7 patients. Blood perfusion was monitored using laser speckle contrast imaging: during surgery, immediately postoperatively (0 weeks), and at follow-up, 1, 3, and 6 weeks after surgery.RESULTS: Perfusion decreased gradually along the length of the flap, and reached a minimum 15 mm from the flap base. Perfusion in the proximal 20 mm of the flap was completely restored after 1 week, while the distal part of the flap was gradually reperfused over 6 weeks. Both the functional and esthetic surgical outcomes were excellent.CONCLUSIONS: The rapid reperfusion of the glabellar flap may be explained by its connection to the vascular network via the flap pedicle. In flaps longer than 20 mm, the distal part can be considered a free skin transplant, and a combination of a glabellar flap and a free skin graft could then be considered.
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| 24. |
- Berggren, Johanna V., et al.
(författare)
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Perfusion Monitoring During Oculoplastic Reconstructive Surgery : A Comprehensive Review
- 2022
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Ingår i: Ophthalmic Plastic and Reconstructive Surgery. - 0740-9303. ; 38:6, s. 522-534
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Forskningsöversikt (refereegranskat)abstract
- PURPOSE: Knowledge of how blood perfusion is affected during and after reconstructive surgery is of great importance to predict the survival of grafts and flaps. When commonly used reconstructive procedures were developed a century ago, they were based on empirical observations of clinical outcome.METHODS: This is a comprehensive literature review that summarizes the current state of knowledge regarding microvascular perfusion monitoring during oculoplastic procedures.RESULTS: Over the years, a number of techniques for perfusion monitoring have been developed as an attempt to be more objective than clinical examination using traditional methods such as observations of skin temperature, turgor, color, smell, and capillary refill time. There are limited publications regarding microvascular perfusion monitoring during reconstructive procedures in the periocular area. Modern laser-based techniques have been attractive due to their noninvasive nature.CONCLUSIONS: Today, modern, noninvasive techniques are available to monitor perfusion during and after surgery. This has increased our knowledge on the perfusion in common oculoplastic surgery procedures. A detailed understanding of how blood perfusion is affected will hopefully allow the improvement of surgical techniques for better clinical outcome.
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| 25. |
- Berggren, Johanna Vennström, et al.
(författare)
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Successful repair of a full upper eyelid defect following traumatic amputation by simply suturing it back in place
- 2019
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Ingår i: JPRAS Open. - : Elsevier BV. - 2352-5878. ; 19, s. 73-76
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Tidskriftsartikel (refereegranskat)abstract
- There is a general belief that a full-thickness eyelid defect is best repaired using a vascularized flap in combination with a free graft, and that a free full-thickness eyelid graft would not survive due to poor blood perfusion. However, we describe a case in which an upper eyelid was traumatically amputated. The eyelid was sutured in place and healed well in situ. The long-term outcome was good regarding motility and function. This raises the question of whether a blood-supplying pedicle is necessary for the survival of the graft when repairing large eyelid defects.
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| 26. |
- Berggren, Johanna V, et al.
(författare)
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The Effect of Canthotomy on Blood Perfusion During the Repair of Lower Eyelid Defects
- 2020
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Ingår i: Ophthalmic Plastic and Reconstructive Surgery. - 1537-2677. ; 36:2, s. 135-138
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Canthotomy is frequently used to mobilize extra tissue when repairing larger lower eyelid defects. The aim of this study was to explore the effect of canthotomy on blood perfusion and oxygen tension.METHODS: Eight pigs underwent a wedge resection of the lower eyelid and canthotomy (with cantholysis involving the lateral palpebral artery). The wedge resection was performed 8, 6, and 4 mm from the canthotomy. Perfusion and oxygen tension were monitored in the eyelid between the wedge resection and canthotomy using laser Doppler velocimetry and a Clark electrode. Verapamil was administered, and measurements were also performed 12 hours after surgery, to investigate the possible effects of vasospasm RESULTS:: The wedge resection alone did not affect perfusion. Canthotomy led to a reduction in perfusion; being 60% when the length of remaining eyelid was 8 mm, 32% when it was 6 mm, and 24% when it was 4 mm. Similar results were observed for oxygen tension. Vasospasm did not affect the results.CONCLUSIONS: Canthotomy in combination with a wedge resection of the lower eyelid affects blood perfusion. A smaller length of remaining eyelid tissue will have less perfusion. This may not have any implications in cases of direct closure, but may play a role when the eyelid is to provide oxygen and nutrients to avascular grafts.
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| 27. |
- Birke-Sorensen, H., et al.
(författare)
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Evidence-based recommendations for negative pressure wound therapy: Treatment variables (pressure levels, wound filler and contact layer) - Steps towards an international consensus
- 2011
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Ingår i: Journal of Plastic, Reconstructive and Aesthetic Surgery. - : Elsevier BV. - 1878-0539 .- 1748-6815. ; 64, s. 1-16
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Forskningsöversikt (refereegranskat)abstract
- Negative pressure wound therapy (NPWT) is becoming a commonplace treatment in many clinical settings. New devices and dressings are being introduced. Despite widespread adoption, there remains uncertainty regarding several aspects of NPWT use. To respond to these gaps, a global expert panel was convened to develop evidence-based recommendations describing the use of NPWT. In a previous communication, we have reviewed the evidence base for the use of NPWT within trauma and reconstructive surgery. In this communication, we present results of the assessment of evidence relating to the different NPWT treatment variables: different wound fillers (principally foam and gauze); when to use a wound contact layer; different pressure settings; and the impact of NPWT on bacterial bioburden. Evidence-based recommendations were obtained by a systematic review of the literature, grading of evidence and drafting of the recommendations by a global expert panel. Evidence and recommendations were graded according to the Scottish Intercollegiate Guidelines Network (SIGN) classification system. In general, there is relatively weak evidence on which to base recommendations for any one NPWT treatment variable over another. Overall, 14 recommendations were developed: five for the choice of wound filler and wound contact layer, four for choice of pressure setting and five for use of NPWT in infected wounds. With respect to bioburden, evidence suggests that reduction of bacteria in wounds is not a major mode of action of NPWT. (C) 2011 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.
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| 28. |
- Bodén, Embla, et al.
(författare)
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Quantitative Proteomics Indicate Radical Removal of Non-Small Cell Lung Cancer and Predict Outcome
- 2022
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Ingår i: Biomedicines. - : MDPI AG. - 2227-9059. ; 10:11
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Tidskriftsartikel (refereegranskat)abstract
- Non-small cell lung cancer (NSCLC) is associated with low survival rates, often due to late diagnosis and lack of personalized medicine. Diagnosing and monitoring NSCLC using blood samples has lately gained interest due to its less invasive nature. In the present study, plasma was collected at three timepoints and analyzed using proximity extension assay technology and quantitative real-time polymerase chain reaction in patients with primary NSCLC stages IA–IIIA undergoing surgery. Results were adjusted for patient demographics, tumor, node, metastasis (TNM) stage, and multiple testing. Major histocompatibility (MHC) class 1 polypeptide-related sequence A/B (MIC-A/B) and tumor necrosis factor ligand superfamily member 6 (FASLG) were significantly increased post-surgery, suggesting radical removal of cancerous cells. Levels of hepatocyte growth factor (HGF) initially increased postoperatively but were later lowered, potentially indicating radical removal of malignant cells. The levels of FASLG in patients who later died or had a relapse of NSCLC were lower at all three timepoints compared to surviving patients without relapse, indicating that FASLG may be used as a prognostic biomarker. The biomarkers were confirmed using microarray data. In conclusion, quantitative proteomics could be used for NSCLC identification but may also provide information on radical surgical removal of NSCLC and post-surgical prognosis.
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| 29. |
- Borgquist, Ola, et al.
(författare)
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Individualizing the Use of Negative Pressure Wound Therapy for Optimal Wound Healing: A Focused Review of the Literature
- 2011
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Ingår i: Ostomy - Wound Management. - 0889-5899. ; 57:4, s. 44-44
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Forskningsöversikt (refereegranskat)abstract
- Currently available research suggests that negative pressure wound therapy (NPWT) creates a moist wound healing environment, drains exudate, reduces tissue edema, contracts the wound edges, mechanically stimulates the wound bed, and influences blood perfusion at the wound edge, which may lead to angiogenesis and the formation of granulation tissue. Although no clear evidence is available that NPWT accelerates wound healing compared to other interventions or that one form of NPWT is better than another, preclinical research suggests that the most commonly used dressings, level of negative pressure, and application mode (continuous, intermittent, or variable) may not be optimal for all patients. To summarize available literature related to these NPWT choices, pertinent literature published between 2005 and 2010 was reviewed. Preclinical study results suggest that the maximal biological effect of NPWT at the wound edge often can be achieved at -80 mm Hg and that foam dressings may be advantageous for large defect wounds, whereas gauze dressings may be more suitable for smaller wounds or when scar formation or pain is a concern. Preclinical research results also suggest that intermittent or variable pressure application has a better effect on granulation tissue formation than continuous application. The variable pressure mode maintains a negative pressure environment at lower pressure settings without dramatic fluctuations inherent to intermittent (on-and-off) pressure. Prospective, controlled clinical studies are needed to compare NPWT to other advanced wound care protocols of care and to ascertain the effect of various NPWT methods and regimens on outcomes of care.
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| 30. |
- Borgquist, Ola, et al.
(författare)
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Measurements of wound edge microvascular blood flow during negative pressure wound therapy using thermodiffusion and transcutaneous and invasive laser Doppler velocimetry
- 2011
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Ingår i: Wound Repair and Regeneration. - 1524-475X. ; 19:6, s. 727-733
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Tidskriftsartikel (refereegranskat)abstract
- The effects of negative pressure wound therapy (NPWT) on wound edge microvascular blood flow are not clear. The aim of the present study was therefore to further elucidate the effects of NPWT on periwound blood flow in a porcine peripheral wound model using different blood flow measurement techniques. NPWT at -20, -40, -80, and -125 mmHg was applied to a peripheral porcine wound (n = 8). Thermodiffusion, transcutaneous, and invasive laser Doppler velocimetry were used to measure the blood perfusion 0.5, 1.0, and 2.5 cm from the wound edge. Thermodiffusion (an invasive measurement technique) generally showed a decrease in perfusion close to the wound edge (0.5 cm), and an increase further from the edge (2.5 cm). Invasive laser Doppler velocimetry showed a similar response pattern, with a decrease in blood flow 0.5 cm from the wound edge and an increase further away. However, 1.0 cm from the wound edge blood flow decreased with high pressure levels and increased with low pressure levels. A different response pattern was seen with transcutaneous laser Doppler velocimetry, showing an increase in blood flow regardless of the distance from the wound edge (0.5, 1.0, and 2.5 cm). During NPWT, both increases and decreases in blood flow can be seen in the periwound tissue depending on the distance from the wound edge and the pressure level. The pattern of response depends partly on the measurement technique used. The combination of hypoperfusion and hyperperfusion caused by NPWT may accelerate wound healing.
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| 31. |
- Borgquist, Ola, et al.
(författare)
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Micro- and macromechanical effects on the wound bed of negative pressure wound therapy using gauze and foam.
- 2010
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Ingår i: Annals of Plastic Surgery. - 1536-3708. ; 64:6, s. 789-793
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Tidskriftsartikel (refereegranskat)abstract
- Negative pressure wound therapy (NPWT) results in 2 types of tissue deformation, macrodeformation (ie, wound contraction) and microdeformation (ie, the interaction of tissue and dressing on a microscopic level). These effects have been delineated for one type of wound filler, foam, but not for gauze. The mechanical deformation initiates a signaling cascade which ultimately leads to wound healing. The aim of the present study was to examine the effect of gauze and foam on macro- and microdeformation during treatment with negative pressure. An in vivo porcine peripheral wound model was used. NPWT was applied for 72 hours at 0, -75, and -125 mm Hg, using either foam or gauze as wound filler. The mechanical effects of NPWT were examined by measuring the wound surface area reduction and by histologic analysis of the wound bed tissue. Similar degrees of wound contraction (macrodeformation) were seen during NPWT regardless if foam or gauze was used. After negative pressure had been discontinued, the wound stayed contracted. There was no difference in wound contraction between -75 and -125 mm Hg. Biopsies of the wound bed revealed a repeating pattern of wound surface undulations and small tissue blebs ("tissue mushrooms") were pulled into the pores of the foam dressing and the spaces between the threads in the gauze dressing (microdeformation). This pattern was obvious in wounds treated both with foam and gauze, at atmospheric pressure (0 mm Hg) as well as at subatmospheric pressures (-75 and -125 mm Hg). The degrees of micro- and macrodeformation of the wound bed are similar after NPWT regardless if foam or gauze is used as wound filler.
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| 32. |
- Borgquist, Ola, et al.
(författare)
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The Effect of Intermittent and Variable Negative Pressure Wound Therapy on Wound Edge Microvascular Blood Flow
- 2010
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Ingår i: Ostomy - Wound Management. - 0889-5899. ; 56:3, s. 60-67
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Tidskriftsartikel (refereegranskat)abstract
- Negative pressure wound therapy (NPWT) alters wound edge microvascular blood flow. Some preclinical data suggest that cycling between low and high negative pressure may be more beneficial than continuous NPWT. The purpose of this in vivo study was to compare the effect of intermittent negative pressure (cycled either from 0 to -75 or to -125 mm Hg) and variable negative pressure (cycled from -10 to -75 or -125 mm Hg or from -45 to -75 or -125 mm Hg) on wound edge microvascular blood flow. Using a peripheral wound model (n = 8 domestic 70-kg pigs), intermittent and variable NPWT was applied to surgically created wounds (5 cm diameter, 2 cm. depth) for five cycles of 5 minutes of high and 2 minutes of low pressure. Blood flow was measured using laser Doppler velocimetry in subcutaneous and muscle tissue at 0.5 and 2.5 cm from the wound edge. When NPWT was applied, blood flow decreased an average of 29% +/- 2% in muscle tissue and 22 % +/- 4% in subcutaneous tissue at -75 mm Hg at 0.5 cm from the wound edge and increased an average of 20% +/- 6% for -75 mm Hg at 2.5 cm from the wound edge. Blood flow changed repeatedly when negative pressure was cycled. Large gradients between the cycled pressures (eg, -10 to -75 mm Hg) resulted in greater blood flow alterations than smaller (eg, -45 to -75 mm Hg) gradients. Blood flow alternations were similar between low-pressure settings of -10 mm Hg (variable NPWT) and 0 mm Hg (intermittent NPWT) and between high-pressure settings of -75 or -125 mm Hg. Both intermittent and variable NPWT result in a beneficial combination of increased blood flow, known to facilitate oxygenation and nutrient supply, and decreased blood flow, known to stimulate angiogenesis and granulation tissue formation. Cycling the negative pressure may be especially advantageous when treating poorly vascularized tissue. In cases where intermittent therapy causes patient discomfort, variable therapy may be superior.
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| 33. |
- Borgquist, Ola, et al.
(författare)
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The influence of low and high pressure levels during negative pressure wound therapy on wound contraction and fluid evacuation.
- 2011
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Ingår i: Plastic and Reconstructive Surgery. - 0032-1052. ; 127:2, s. 551-559
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Negative pressure wound therapy (NPWT) promotes healing by drainage of excessive fluid and debris and also by mechanical deformation of the wound edge tissue. The most commonly used negative pressure is -125 mmHg. However, this pressure may cause pain and ischemia, and the pressure often needs to be reduced. The aim of the present study was to examine wound contraction and fluid removal during low and increasing levels of negative pressures. METHODS: A peripheral wound was created in 70 kg pigs. The immediate effects of NPWT (-10 to -175 mmHg) on wound contraction and fluid removal was studied in eight pigs. The long-term effects on wound contraction were studied in eight additional pigs during 72 hours of NPWT at -75 mmHg. RESULTS: The wound contraction and fluid removal increased gradually with increasing levels of negative pressure until reaching a steady state. Maximum wound contraction was observed at -75 mmHg. When NPWT was discontinued, after 72 hours of therapy, the wound surface area was smaller than before therapy. Maximum wound fluid removal was observed at -125 mmHg. Higher pressures did not further reduce wound surface area or fluid volume. The time required for evacuation of 50% of the maximal fluid drained for a specific pressure level was longer for low negative pressures (∼45 s for pressures below -50 mmHg) than for high negative pressures (∼15-20 s for pressures above -50 mmHg). CONCLUSIONS: NPWT facilitates drainage of wound fluid and exudates and results in mechanical deformation of the wound edge tissue which is known to stimulate granulation tissue formation. Maximum wound contraction is achieved already at -75 mmHg, and this may be a suitable pressure for most wounds. In wounds with large volumes of exudate, higher pressure levels may be needed for the initial treatment period.
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| 34. |
- Borgquist, Ola, et al.
(författare)
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Tissue Ingrowth Into Foam but Not Into Gauze During Negative Pressure Wound Therapy
- 2009
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Ingår i: Wounds. - 1044-7946. ; 21:11, s. 302-309
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Tidskriftsartikel (refereegranskat)abstract
- Background. Foam and gauze are two types of wound fillers used for negative pressure wound therapy (NPWT). Differences in the wound healing effects of foam and gauze have been observed clinically. The aim of the present study was to examine the effects of NPWT on the wound bed using foam and gauze. Methods. A porcine peripheral wound model was treated with NPWT at 0, -75 mmHg, or -125 mmHg for 72 hours. The effects of foam and gauze on the wound bed were compared, and the force required to remove the dressings was measured. Sections of biopsies from the wound bed with an overlying dressing were stained with hematoxylin-eosin and Giemsa and were examined histologically. Results. The force ratio needed to remove the wound filler from the wound bed after treatment with negative pressure was greater for foam than for gauze. NPWT caused the wound bed tissue to grow into the foam, while there was I no such ingrowth into gauze. Furthermore, beneath the foam there was more leukocyte infiltration, tissue disorganization, disruption of contact among cells, and differences in size among cells. The results were similar regardless of the level of negative pressure. Conclusion. More force was required to remove foam compared to gauze following NPWT, which may have been due to greater ingrowth into foam. These findings may explain the patient discomfort and wound bed disruption upon removal of foam. The observed differences in wound bed tissue morphology under foam and gauze are in accordance with the clinically observed differences in quality of granulation tissue formation.
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| 35. |
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| 36. |
- Borgquist, Ola, et al.
(författare)
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Wound edge microvascular blood flow during negative-pressure wound therapy: examining the effects of pressures from -10 to -175 mmHg.
- 2010
-
Ingår i: Plastic and Reconstructive Surgery. - 0032-1052. ; 125:2, s. 502-509
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Negative-pressure wound therapy is believed to accelerate wound healing by altered wound edge microvascular blood flow. The current standard negative pressure is -125 mmHg. However, this pressure may cause pain and ischemia and often has to be reduced. The aim of the present study was to examine the blood flow effects of different levels of negative pressures (-10 to -175 mmHg). METHODS: Wound edge microvascular blood flow was studied in a peripheral wound model in eight 70-kg pigs on application of negative-pressure wound therapy. Blood flow was examined, using laser Doppler velocimetry, in subcutaneous and muscle tissue at 0.5, 2.5, and 5 cm from the wound edge. RESULTS: Blood flow changed gradually with increasing negative pressure until reaching a steady state. Blood flow decreased close to the wound edge (0.5 cm) and increased farther from the wound edge (2.5 cm). At 0.5 cm, blood flow decreased 15 percent at -10 mmHg, 64 percent at -45 mmHg, and 97 percent at -80 mmHg. At 2.5 cm, blood flow increased 6 percent at -10 mmHg, 32 percent at -45 mmHg, and 90 percent at -80 mmHg. Higher levels of negative pressure did not have additional blood flow effects (p > 0.30). No blood flow effects were seen 5 cm from the wound edge. CONCLUSIONS: Blood flow changes gradually when the negative pressure is increased. The levels of pressure for negative-pressure wound therapy may be tailored depending on the wound type and tissue composition, and this study implies that -80 mmHg has similar blood flow effects as the clinical standard, -125 mmHg.
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| 37. |
- Broberg, Ellen, et al.
(författare)
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Releasing high positive end-expiratory pressure to a low level generates a pronounced increase in particle flow from the airways
- 2023
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Ingår i: Intensive Care Medicine Experimental. - : Springer Science and Business Media LLC. - 2197-425X. ; 11:1
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives: Detecting particle flow from the airways by a non-invasive analyzing technique might serve as an additional tool to monitor mechanical ventilation. In the present study, we used a customized particles in exhaled air (PExA) technique, which is an optical particle counter for the monitoring of particle flow in exhaled air. We studied particle flow while increasing and releasing positive end-expiratory pressure (PEEP). The aim of this study was to investigate the impact of different levels of PEEP on particle flow in exhaled air in an experimental setting. We hypothesized that gradually increasing PEEP will reduce the particle flow from the airways and releasing PEEP from a high level to a low level will result in increased particle flow. Methods: Five fully anesthetized domestic pigs received a gradual increase of PEEP from 5 cmH2O to a maximum of 25 cmH2O during volume-controlled ventilation. The particle count along with vital parameters and ventilator settings were collected continuously and measurements were taken after every increase in PEEP. The particle sizes measured were between 0.41 µm and 4.55 µm. Results: A significant increase in particle count was seen going from all levels of PEEP to release of PEEP. At a PEEP level of 15 cmH2O, there was a median particle count of 282 (154–710) compared to release of PEEP to a level of 5 cmH2O which led to a median particle count of 3754 (2437–10,606) (p < 0.009). A decrease in blood pressure was seen from baseline to all levels of PEEP and significantly so at a PEEP level of 20 cmH2O. Conclusions: In the present study, a significant increase in particle count was seen on releasing PEEP back to baseline compared to all levels of PEEP, while no changes were seen when gradually increasing PEEP. These findings further explore the significance of changes in particle flow and their part in pathophysiological processes within the lung.
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| 38. |
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| 39. |
- Bunke, Josefine, et al.
(författare)
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Extended-wavelength diffuse reflectance spectroscopy for a comprehensive view of blood perfusion and tissue response in human forearm skin
- 2019
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Ingår i: Microvascular Research. - : Elsevier BV. - 1095-9319 .- 0026-2862. ; 124, s. 1-5
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The aim of this study was to investigate the possibility of using extended-wavelength diffuse reflectance spectroscopy (EW-DRS) to measure tissue response related to blood perfusion. The study was performed on a model that we have previously found to be useful for studying techniques for perfusion monitoring following the injection of epinephrine in a local anesthetic in the human forearm.METHODS: Nine healthy subjects were included in the study. Spectroscopy was performed with an EW-DRS system using a combination of two spectrometers to resolve light in the visible (350 nm to 1100 nm) and the near-infrared regions (900 nm to 1700 nm). The change in signal upon the injection of lidocaine (20 mg/ml) + epinephrine (12.5 μg/ml) (LIDO +EPI), compared to a control injection with saline (9 mg/ml), was investigated.RESULTS: Injection of lidocaine + epinephrine (12.5 μg/ml) caused a change in the EW-DRS signal in the wavelength intervals 510 to 610 nm, known to change upon deoxygenation of hemoglobin. When examining the full wavelength range (450 to 1550 nm) a decrease in reflectance upon LIDO +EPI injection was observed, suggesting that the broader spectrum provides more detailed information on the tissue response. The time to stable hypoperfusion was found to be 2.6 min.CONCLUSIONS: EW-DRS appears to be a promising technique for monitoring perfusion, and could provide a useful tool in plastic and reconstructive surgery. The broad spectrum provides detailed information on the molecular changes taking place in the tissue. However, the technique must be thoroughly validated before it can be implemented in clinical practice.
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| 40. |
- Bunke, Josefine, et al.
(författare)
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Hyperspectral and Laser Speckle Contrast Imaging for Monitoring the Effect of Epinephrine in Local Anesthetics in Oculoplastic Surgery
- 2022
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Ingår i: Ophthalmic Plastic and Reconstructive Surgery. - 1537-2677. ; 38:5, s. 462-468
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Epinephrine is used in local anesthetics to induce vasoconstriction and thus reduce bleeding and prolong the anesthetic effect. Finding the optimal delay between the administration of the anesthetic and skin incision to ensure vasoconstriction and minimize bleeding is important and has recently become the subject of debate. This is the first study to assess blood perfusion and oxygen saturation (sO2) simultaneously in response to a local anesthetic containing epinephrine in human oculoplastic surgery.METHODS: A local anesthetic consisting of lidocaine and epinephrine (20 mg/ml + 12.5 μg/ml) was injected in the eyelids of 9 subjects undergoing blepharoplasty. The perfusion and sO2 of the eyelids were monitored using laser speckle contrast imaging and hyperspectral imaging, respectively.RESULTS: Laser speckle contrast imaging monitoring showed a decrease in perfusion over time centrally at the site of injection. Half-maximum effect was reached after 34 seconds, and full effect after 115 seconds, determined by exponential fitting. The drop in perfusion decreased gradually further away from the injection site and hypoperfusion was less prominent 4 mm from the injection site, with a spatially dependent half-maximum effect of 231 seconds. Hyperspectral imaging showed only a slight decrease in sO2 of 11 % at the injection site.CONCLUSIONS: The optimal time delay for skin incision in oculoplastic surgery is approximately 2 minutes after the injection of lidocaine with epinephrine. Longer delay does not lead to a further decrease in perfusion. As sO2 was only slightly reduced after injection, the results indicate that the use of epinephrine is safe in the periocular region.
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| 41. |
- 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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| 42. |
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| 43. |
- Chaudhry, Nadia, et al.
(författare)
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Breast Cancer Diagnosis Using Extended-Wavelength–Diffuse Reflectance Spectroscopy (EW-DRS) : Proof of Concept in Ex Vivo Breast Specimens Using Machine Learning
- 2023
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Ingår i: Diagnostics. - 2075-4418. ; 13:19, s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- This study aims to investigate the feasibility of using diffuse reflectance spectroscopy (DRS) to distinguish malignant breast tissue from adjacent healthy tissue, and to evaluate if an extended-wavelength range (450–1550 nm) has an advantage over the standard wavelength range (450–900 nm). Multivariate statistics and machine learning algorithms, either linear discriminant analysis (LDA) or support vector machine (SVM) are used to distinguish the two tissue types in breast specimens (total or partial mastectomy) from 23 female patients with primary breast cancer. EW-DRS has a sensitivity of 94% and specificity of 91% as compared to a sensitivity of 40% and specificity of 71% using the standard wavelength range. The results suggest that DRS can discriminate between malignant and healthy breast tissue, with improved outcomes using an extended wavelength. It is also possible to construct a simple analytical model to improve the diagnostic performance of the DRS technique.
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| 44. |
- Dahlstrand, Ulf, et al.
(författare)
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Extended-wavelength diffuse reflectance spectroscopy with a machine-learning method for in vivo tissue classification
- 2019
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 14:10
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: An extended-wavelength diffuse reflectance spectroscopy (EWDRS) technique was evaluated for its ability to differentiate between and classify different skin and tissue types in an in vivo pig model.MATERIALS AND METHODS: EWDRS recordings (450-1550 nm) were made on skin with different degrees of pigmentation as well as on the pig snout and tongue. The recordings were used to train a support vector machine to identify and classify the different skin and tissue types.RESULTS: The resulting EWDRS curves for each skin and tissue type had a unique profile. The support vector machine was able to classify each skin and tissue type with an overall accuracy of 98.2%. The sensitivity and specificity were between 96.4 and 100.0% for all skin and tissue types.CONCLUSION: EWDRS can be used in vivo to differentiate between different skin and tissue types with good accuracy. Further development of the technique may potentially lead to a novel diagnostic tool for e.g. non-invasive tumor margin delineation.
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| 45. |
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| 46. |
- 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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| 47. |
- Dahlstrand, Ulf, et al.
(författare)
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Photoacoustic Imaging of Enucleated Eyes from Patients with Uveal Melanoma can Reveal Extrascleral Growth
- 2021
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Ingår i: Open Ophthalmology Journal. - : Bentham Science Publishers Ltd.. - 1874-3641. ; 15:1, s. 270-276
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Tidskriftsartikel (refereegranskat)abstract
- Background:Uveal melanoma is treated by either enucleation (removal of the eye) or local eye-sparing therapies, depending on tumor size and whether there are signs of extrascleral growth. Photoacoustic (PA) imaging is a novel imaging modality that provides high-resolution images of the molecular composition of tissues.Objective:In this study, the feasibility of PA imaging for uveal melanomas and detection of extrascleral growth was explored.Methods:Seven enucleated human eyes with uveal melanomas were examined using PA imaging. The spectral signatures of the melanomas and the layers of the normal eyewall were characterized using 59 excitation wavelengths from 680 to 970 nm.Results:Significant differences were seen between the spectra obtained from melanoma and the healthy eyewall. Using spectral unmixing, melanin, hemoglobin and collagen could be mapped out, showing the architecture of the tumor in relation to the eyewall. This allowed visualization of regions where the tumor extended into the extrascleral space.Conclusion:PA imaging appears to have the potential to aid in assessing uveal melanomas and as a diagnostic tool for the detection of extrascleral growth.
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| 48. |
- Dahlstrand, Ulf, et al.
(författare)
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Spectral Signatures in the Different Layers of the Human Eyelid by Photoacoustic Imaging
- 2019
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Ingår i: Lasers in Surgery and Medicine. - : Wiley. - 0196-8092 .- 1096-9101.
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND OBJECTIVES: The eyelids are susceptible to a number of skin cancers, which are challenging to excise radically without sacrificing excessive healthy tissue. Photoacoustic (PA) imaging is an emerging non-invasive biomedical imaging modality that could potentially be used for intraoperative micrographic control of the surgical margins of eyelid tumors. In this study, non-cancerous human eyelid tissue was characterized using PA as a first step in the development of this technique.STUDY DESIGN/MATERIALS AND METHODS: Twelve full-thickness samples from nine patients were analyzed ex vivo using PA imaging. Two-dimensional PA images were acquired using 59 wavelengths in the range of 680-970 nm to obtain the spectral signatures of the skin, orbicularis oculi muscle, and the tarsal plate. Three-dimensional images were obtained by scanning the tissues using a linear stepping motor. Spectral unmixing was performed to visualize the chromophore distribution.RESULTS: The resulting PA spectra could be used to differentiate between the orbicularis oculi muscle and the other two structures (P < 0.05). The signals from the skin and the tarsal plate were more similar in appearance, probably due to similarities in their molecular composition. Spectral unmixing provided a clear visualization of the overall architecture of the eyelids.CONCLUSIONS: PA imaging can be used to differentiate between the orbicularis oculi muscle and the eyelid skin and tarsal plate. The main structures of human eyelids could be visualized in three dimensions using PA imaging. This technique could potentially be used to examine eyelid tumors intraoperatively in the future. However, further studies on tumors in vivo are needed before considering such clinical use. Lasers Surg Med. © 2019 Wiley Periodicals, Inc.
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| 49. |
- Dimitrijevic, Ivan, et al.
(författare)
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Increased angiotensin II type 1 receptor expression in temporal arteries from patients with giant cell arteritis.
- 2009
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Ingår i: Ophthalmology. - : Elsevier BV. - 1549-4713 .- 0161-6420. ; 116:5, s. 990-996
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Currently, giant cell arteritis (GCA) is primarily treated with corticosteroids or immunomodulating agents, but there is interest in identifying other noncorticosteroid alternatives. Similarities exist in the injury pathways between GCA and atherosclerosis. Angiotensin II is a vasoactive peptide involved in vessel inflammation during atherosclerosis, and angiotensin II receptor inhibitors are effective in preventing atherosclerosis. The present study was performed to elucidate the role of angiotensin type 1 (AT(1)) and type 2 (AT(2)) receptors in GCA. DESIGN: Experimental retrospective immunohistochemical study of temporal arteries using archival formalin-fixed, paraffin-embedded tissue. PARTICIPANTS: Ten patients with GCA and 10 control patients, who were clinically suspected of having GCA but were diagnosed as not having GCA, were included. METHODS: Immunohistochemistry, using anti-AT(1) and anti-AT(2) antibodies, was performed on formalin-fixed and paraffin-embedded temporal arteries. MAIN OUTCOME MEASURES: AT(1) and AT(2) receptor immunostaining intensity was quantified. RESULTS: Hematoxylin-eosin-stained sections of temporal arteries from patients with GCA showed intimal hyperplasia, internal elastic lamina degeneration, and band-shaped infiltrates of inflammatory cells, including lymphocytes, histocytes, and multinucleated giant cells. AT(1) receptor staining was primarily observed in the medial layer of the temporal arteries and was higher in the patients with GCA than in the control patients. This was a result of increased AT(1) receptor immunostaining of both vascular smooth muscle cells and infiltrating inflammatory cells. Only faint immunostaining was seen for AT(2) receptors, primarily in the endothelial cells, and to a lesser extent on the smooth muscle cells. Immunostaining with antibodies for the AT(2) receptor was similar in the patients with GCA and in controls. CONCLUSIONS: These results suggest that AT(1) receptors play a role in the development of GCA. Inhibition of the angiotensin system may thus provide a noncorticosteroid alternative for the treatment of GCA. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.
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- Dimitrijevic, Ivan, et al.
(författare)
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Increased expression of vascular endothelin type B and angiotensin type 1 receptors in patients with ischemic heart disease
- 2009
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Ingår i: BMC Cardiovascular Disorders. - : Springer Science and Business Media LLC. - 1471-2261. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Background: Endothelin-1 and angiotensin II are strong vasoconstrictors. Patients with ischemic heart disease have elevated plasma levels of endothelin-1 and angiotensin II and show increased vascular tone. The aim of the present study was to examine the endothelin and angiotensin II receptor expression in subcutaneous arteries from patients with different degrees of ischemic heart disease. Methods: Subcutaneous arteries were obtained, by biopsy from the abdomen, from patients undergoing coronary artery bypass graft (CABG) surgery because of ischemic heart disease (n = 15), patients with angina pectoris without established myocardial infarction (n = 15) and matched cardiovascular healthy controls (n = 15). Endothelin type A ( ETA) and type B (ETB), and angiotensin type 1 (AT(1)) and type 2 (AT(2)) receptors expression and function were examined using immunohistochemistry, Western blot and in vitro pharmacology. Results: ETA and, to a lesser extent, ETB receptor staining was observed in the healthy vascular smooth muscle cells. The level of ETB receptor expression was higher in patients undergoing CABG surgery (250% +/- 23%; P < 0.05) and in the patients with angina pectoris (199% +/- 6%; P < 0.05), than in the healthy controls (100% +/- 28%). The data was confirmed by Western blotting. Arteries from CABG patients showed increased vasoconstriction upon administration of the selective ETB receptor agonist sarafotoxin S6c, compared to healthy controls (P < 0.05). No such difference was found for the ETA receptors. AT(1) and, to a lesser extent, AT(2) receptor immunostaining was seen in the vascular smooth muscle cells. The level of AT(1) receptor expression was higher in both the angina pectoris (128% +/- 25%; P < 0.05) and in the CABG patients (203% +/- 41%; P < 0.05), as compared to the healthy controls (100% +/- 25%). The increased AT(1) receptor expression was confirmed by Western blotting. Myograph experiment did however not show any change in vasoconstriction to angiotensin II in CABG patients compared to healthy controls (P = n.s). Conclusion: The results demonstrate, for the first time, upregulation of ETB and AT(1) receptors in vascular smooth muscle cells in ischemic heart disease. These receptors may play a role in the pathophysiology of ischemic heart disease and could provide important targets for pharmaceutical interventions.
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