| 1. |
- Elawa, Sherif, et al.
(författare)
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Intestinal obstruction following harvest of VRAM-flap for reconstruction of a large perineal defect
- 2015
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Ingår i: Case Reports in Plastic Surgery and Hand Surgery. - : Taylor & Francis Group. - 2332-0885. ; 2:3-4, s. 88-91
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Tidskriftsartikel (refereegranskat)abstract
- A patient with locally advanced adenocarcinoma of the rectum was operated with abdominoperineal resection and perineal reconstruction with a vertical rectus abdominis musculocutaneous flap. Six days postoperatively, there was herniation of the small bowel, between the anterior and posterior rectus sheaths, to a subcutaneous location.
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| 2. |
- Elawa, Sherif, et al.
(författare)
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Microcirculatory changes in the skin after postmastectomy radiotherapy in women with breast cancer
- 2024
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Postmastectomy radiotherapy (PMRT) increases the risk for complications after breast reconstruction. The pathophysiological mechanism underlying this increased risk is not completely understood. The aim of this study was to examine if there is a relationship between PMRT and microvascular perfusion in the skin directly after, and at 2 and 6 months after PMRT and to assess if there is impaired responsiveness to a topically applied vasodilator (Methyl nicotinate-MN) after PMRT. Skin microvascular responses after PMRT were measured on two sites in the irradiated chest wall of 22 women before, immediately after, and at 2 and 6 months after unilateral PMRT with the contralateral breast as a control. A significant increase in basal skin perfusion was observed in the irradiated chest wall immediately after RT (p < 0.0001). At 2 and 6 months after RT, there was no longer a difference in basal skin perfusion compared to the contralateral breast and compared to baseline. Similarly, the blood flow response in the skin after application of MN was stronger immediately after RT compared to before RT (p < 0.0001), but there was no difference at later time points. These results indicate that the increased risk for complications after surgical procedures are not directly related to changes in skin perfusion and microvascular responsiveness observed after postmastectomy RT.
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| 3. |
- Elawa, Sherif, 1988-
(författare)
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Microvascular Function Assessment after Mastectomy and Radiation Therapy in Breast Cancer Patients : From Methodology to Clinical Application
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Post-mastectomy radiotherapy (PMRT) is an important part of the treatment of breast cancer. It reduces the risk of recurrence and improves overall survival. Scaring and fibrotization of the skin and subcutaneous tissue of the chest wall or remaining breast are among its side-effects. These late side-effects of PMRT may in turn affect skin microcirculation and oxygenation, although this connection is not completely established. In patients that later require breast reconstruction, it is difficult as a plastic surgeon to evaluate if the microcirculatory changes have been affected by PMRT, and how such effects should have an impact on the choice of reconstructive method. In the work presented in this thesis, laser speckle contrast imaging (LSCI), laser-doppler flowmetry (LDF) and diffuse reflectance spectroscopy (DRS) have been used with a strong vasodilator, methyl nicotinate (MN) to study the microcirculatory changes after PMRT.In studies I and II, we aimed to find the optimal concentration of MN and its main mechanisms of action. In healthy volunteers, the microvascular response to different concentrations of MN was evaluated on the forearm using LSCI. It was found that a concentration of 20 mmol/l resulted in a quick vasodilatory response with a long plateau phase, minimal tissue edema and no non-responders. In study II, we utilized locally administered drugs to block the three main pathways responsible for skin vasodilation. Subsequently, we provoked the skin with MN and assessed its effect with LSCI. From this study we could conclude that MN’s mechanism of action is largely mediated by prostaglandins and partly by local sensory nerves.In study III, we examined the skin microcirculatory response in breast cancer patients before, immediately after, and at two and six months following unilateral PMRT, using the contralateral breast as a control. A significant increase in basal skin perfusion and perfusion after application of MN was observed on the irradiated chest wall immediately after RT compared to the contralateral breast and compared to before RT. At six months after RT, there was no longer a difference in basal skin perfusion or after application of MN in the irradiated chest wall compared to the contralateral breast and compared to before RT was given. The results from this study concluded that skin perfusion in the irradiated chest wall had returned to normal when measured six months after RT.In study IV, the late effects on skin microvascular function were studied in women who had undergone mastectomy and PMRT several years prior to the study. Skin perfusion and oxygen saturation was measured with white light diffuse reflectance spectroscopy (DRS) combined with Laser Doppler Flowmetry (LDF) before and after application of MN on the irradiated chest wall with the contralateral non-irradiated breast as control. In this study we found that skin perfusion and oxygenation in the breast are affected several years after radiotherapy and that our method could be a valuable clinical tool prior to deciding surgical procedures after PMRT.To conclude, MN can be topically applied to the skin to reliably assess microvascular function and the microvascular capacity. LSCI and LDF have different strengths and drawbacks, with LSCI having the advantage of having a large spatial resolution that allows for measurements of control areas in the same field of view as the provoked areas. LDF in combination with DRS enabled us to further assess perfusion and oxygenation simultaneously which could be an advantage in fibrotic skin where skin perfusion and oxygen saturation may not correlate with each other. Although the study groups differed between the study examining the early effects of PMRT with the late effects of PMRT, we have been able to non-invasively visualize changes in microcirculation in relation to the acute and chronic phase after PMRT. Future studies are needed to investigate the value of pre-operative measurements with MN provocation for predicting surgical outcome.
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| 4. |
- Elawa, Sherif, et al.
(författare)
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Skin blood flow response to topically applied methyl nicotinate: Possible mechanisms
- 2020
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Ingår i: Skin research and technology. - : WILEY. - 0909-752X .- 1600-0846. ; 26:3, s. 343-348
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Tidskriftsartikel (refereegranskat)abstract
- Background Methyl nicotinate (MN) induces a local cutaneous erythema in the skin and may be valuable as a local provocation in the assessment of microcirculation and skin viability. The mechanisms through which MN mediates its vascular effect are not fully known. The aim of this study was to characterize the vasodilatory effects of topically applied MN and to study the involvement of nitric oxide (NO), local sensory nerves, and prostaglandin-mediated pathways. Methods MN was applied on the skin of healthy subjects in which NO-mediated (L-NMMA), nerve-mediated (lidocaine/prilocaine), and cyclooxygenase-mediated (NSAID) pathways were selectively inhibited. Microvascular responses in the skin were measured using laser speckle contrast imaging (LSCI). Results NSAID reduced the MN-induced perfusion increase with 82% (P < .01), whereas lidocaine/prilocaine reduced it with 32% (P < .01). L-NMMA did not affect the microvascular response to MN. Conclusion The prostaglandin pathway and local sensory nerves are involved in the vasodilatory actions of MN in the skin.
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| 5. |
- Elawa, Sherif, et al.
(författare)
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Skin perfusion and oxygen saturation after mastectomy and radiation therapy in breast cancer patients
- 2024
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Ingår i: Breast. - : Elsevier. - 0960-9776 .- 1532-3080. ; 75
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Tidskriftsartikel (refereegranskat)abstract
- The pathophysiological mechanism behind complications associated with postmastectomy radiotherapy (PMRT) and subsequent implant-based breast reconstruction are not completely understood. The aim of this study was to examine if there is a relationship between PMRT and microvascular perfusion and saturation in the skin after mastectomy and assess if there is impaired responsiveness to a topically applied vasodilator (Methyl nicotinate - MN). Skin microvascular perfusion and oxygenation >2 years after PMRT were measured using white light diffuse reflectance spectroscopy (DRS) and laser Doppler flowmetry (LDF) in the irradiated chest wall of 31 women with the contralateral breast as a control. In the non-irradiated breast, the perfusion after application of MN (median 0.84, 25th-75th centile 0.59-1.02 % RBC × mm/s) was higher compared to the irradiated chest wall (median 0.51, 25th-75th centile 0.21-0.68 % RBC × mm/s, p < 0.001). The same phenomenon was noted for saturation (median 91 %, 25th-75th centile 89-94 % compared to 89 % 25th-75th centile 77-93 %, p = 0.001). Eight of the women (26%) had a ≥10 % difference in skin oxygenation between the non-irradiated breast and the irradiated chest wall. These results indicate that late microvascular changes caused by radiotherapy of the chest wall significantly affect skin perfusion and oxygenation.
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| 6. |
- Elawa, Sherif, et al.
(författare)
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Sympathetic and vagal interaction in the control of cardiac pacemaker rhythm in the guinea-pig heart: Importance of expressing heart rhythm using an appropriate metric
- 2022
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Ingår i: Autonomic Neuroscience. - : ELSEVIER. - 1566-0702 .- 1872-7484. ; 243
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Tidskriftsartikel (refereegranskat)abstract
- There are many reports that, through pre-and post-junctional mechanisms, sympathetic and parasympathetic (vagal) nerves can interact in the control of heart rate. The predominant interaction is accentuated antagonism (AA), where the bradycardia produced by vagal stimulation (VNS) is amplified when heart rate has been increased by sympathetic stimulation (SNS) or beta-adrenergic agonists. The acetylcholine-activated potassium current (IK,Ach), is the primary driver of vagal bradycardia. To examine the participation of IK,Ach in AA, a series of experiments was performed on isolated, double innervated, guinea-pig atrial preparations. Vagal bradycardia was elicited by 10-s trains (1, 2, 5 and 7.5 Hz) or single bursts of VNS (3 stimuli at 50 Hz) before and during acceleration of HR by either SNS (1-3 Hz) or isoprenaline (ISO), in both absence and presence of tertiapin-Q (TQ-IK,Ach blocker). When expressed as an absolute change in HR (beats/min), bradycardia produced by VNS trains was amplified (AA) at all frequencies of VNS in ISO, and at 5 and 7.5 Hz during SNS. Bradycardia in response to 1 and 2 Hz VNS was reduced during SNS. In TQ, only the bradycardia produced by 5 and 7.5 Hz VNS in ISO was amplified. The bradycardia produced by a single burst of VNS was amplified in both ISO and SNS. After TQ the bradycardia in response to a VNS burst was unchanged in ISO, while it was reduced during SNS. When these data were adjusted to account for the increase in baseline HR brought about by SNS and ISO, there was no longer evidence of AA. Diminished responses to low frequencies of VNS (1 and 2 Hz) persisted, and were also seen during IK,Ach block by TQ. We applied the same adjustment to data from 20 published studies. In 8 studies all data indicated AA; 3 studies provided no evidence for AA, and in 9 studies evidence was mixed. There is no doubt that AA can occur in the control of heart rhythm during simultaneous SNS and VNS, but conditions which determine its occurrence, and the mechanisms involved in this interaction remain unclear.
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| 7. |
- Elawa, Sherif, et al.
(författare)
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The microvascular response in the skin to topical application of methyl nicotinate : Effect of concentration and variation between skin sites
- 2019
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Ingår i: Microvascular Research. - : Academic Press. - 0026-2862 .- 1095-9319. ; 124, s. 54-60
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundMethyl nicotinate (MN) induces a local cutaneous erythema in the skin and may be used as a local provocation in the assessment of microcirculation and skin viability. The aims were to measure the effects of increasing doses of MN, to find the concentration that yields the most reproducible effect from day to day and between sites, and to study the variation between skin sites.MethodsMicrovascular responses to topically applied MN at different concentrations were measured in 12 subjects on separate days and on contralateral sides, using laserspeckle contrast imaging (LSCI). MN effects were measured in four different body sites.ResultsAt 20 mmol/L, the response to MN was most reproducible day-to-day and site-to-site, and resulted in a plateau response between 5 and 20 min after application.The skin region of the lower back had a lower perfusion value compared to the epigastric region (p = 0.007). When responses were compared to nearby, unprovoked areas, a significantly larger increase in perfusion was seen in the forearm, compared to all other anatomical sites (p < 0.03).ConclusionA concentration of 20 mmol/L MN generated the most reproducible microvascular response in the skin. The response varies between different body sites.
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| 8. |
- Karlsson, Matilda, et al.
(författare)
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Biosynthetic cellulose compared to porcine xenograft in the treatment of partial-thickness burns : A randomised clinical trial.
- 2022
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Ingår i: Burns. - : Elsevier. - 0305-4179 .- 1879-1409. ; 48:5, s. 1236-1245
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Tidskriftsartikel (refereegranskat)abstract
- AIM: The aim was to compare two dressing treatments for partial-thickness burns: biosynthetic cellulose dressing (BsC) (Epiprotect® S2Medical AB, Linköping, Sweden) and porcine xenograft (EZ Derm®, Mölnlycke Health Care, Gothenburg, Sweden).METHODS: Twenty-four adults with partial-thickness burns were included in this randomized clinical trial conducted at The Burn Centers in Linköping and Uppsala, Sweden between June 2016 and November 2018. Time to healing was the primary outcome. Secondary outcomes were wound infection, pain, impact on everyday life, length of hospital stay, cost, and burn scar outcome (evaluated with POSAS).RESULTS: We found no significant differences between the two dressing groups regarding time to healing, wound infection, pain, impact on everyday life, duration of hospital stay, cost, or burn scar outcome at the first follow up. Burn scar outcome at the 12-month follow up showed that the porcine xenograft group patients scored their scars higher on the POSAS items thickness (p = 0.048) and relief (p = 0.050). This difference was, however, not confirmed by the observer.CONCLUSIONS: The results showed the dressings performed similarly when used in adults with burns evaluated as partial thickness.
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| 9. |
- Zötterman, Johan, et al.
(författare)
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Correlation between Indocyanine Green Fluorescence Angiography and Laser Speckle Contrast Imaging in a Flap Model
- 2023
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Ingår i: Plastic and Reconstructive Surgery - Global Open. - : LIPPINCOTT WILLIAMS & WILKINS. - 2169-7574. ; 11:9
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Tidskriftsartikel (refereegranskat)abstract
- Background:Indocyanine green fluorescence angiography (ICG-FA) is used to assess tissue intraoperatively in reconstructive surgery. This requires an intra-venous dye injection for each assessment. This is not necessary in laser speckle contrast imaging (LSCI); therefore, this method may be better suited for tissue evaluation. To determine this, we compared the two methods in a porcine flap model.Methods:One random and one pedicled flap were raised on each buttock of six animals. They were assessed with LSCI at baseline, when raised (T0), at 30 minutes (T30) and with ICG-FA at T0 and T30. Regions of interest (ROI) were chosen along the flap axis. Perfusion, measured as perfusion units (PU) in the LSCI assessment and pixel-intensity for the ICG-FA video uptake, was calculated in the ROI. Correlation was calculated between PU and pixel-intensity measured as time to peak (TTP) and area under curve for 60 seconds (AUC60).Results:Correlation between LSCI and AUC60 for the ICG-FA in corresponding ROI could be seen in all flaps at all time points. The correlation was higher for T0 (r=0.7 for random flap and r=0.6 for pedicled flap) than for T30 (r=0.57 for random flap and r=0.59 for pedicled flap). Even higher correlation could be seen PU and TTP (T0: random flap r=-0.8 and pedicled flap r=0.76. T30: random flap r=-0.8 and pedicled flap r=0.71)Conclusion:There is a correlation between PU from LSCI and TTP and AUC60 for ICG-FA, indicating that LSCI could be considered for intraoperative tissue assessment.
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