| 51. |
- Sjöström, Martin, et al.
(författare)
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Evaluation of MODIS gross primary productivity for Africa using eddy covariance data
- 2013
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Ingår i: Remote Sensing of Environment. - : Elsevier BV. - 0034-4257. ; 131, s. 275-286
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Tidskriftsartikel (refereegranskat)abstract
- MOD17A2 provides operational gross primary production (GPP) data globally at 1 km spatial resolution and 8-day temporal resolution. MOD17A2 estimates GPP according to the light use efficiency (LUE) concept assuming a fixed maximum rate of carbon assimilation per unit photosynthetically active radiation absorbed by the vegetation (epsilon(max)). Minimum temperature and vapor pressure deficit derived from meteorological data down-regulate epsilon(max) and constrain carbon assimilation. This data is useful for regional to global studies of the terrestrial carbon budget, climate change and natural resources. In this study we evaluated the MOD17A2 product and its driver data by using in situ measurements of meteorology and eddy covariance GPP for 12 African sites. MOD17A2 agreed well with eddy covariance GPP for wet sites. Overall, seasonality was well captured but MOD17A2 GPP was underestimated for the dry sites located in the Sahel region. Replacing the meteorological driver data derived from coarse resolution reanalysis data with tower measurements reduced MOD17A2 GPP uncertainties, however, the underestimations at the dry sites persisted. Inferred epsilon(max) calculated from tower data was higher than the epsilon(max) prescribed in MOD17A2. This, in addition to uncertainties in fraction of absorbed photosynthetically active radiation (FAPAR) explains some of the underestimations. The results suggest that improved quality of driver data, but primarily a readjustment of the parameters in the biome parameter look-up table (BPLUT) may be needed to better estimate GPP for African ecosystems in MOD17A2. (C) 2013 Elsevier Inc. All rights reserved.
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| 52. |
- Sjöström, Martin, et al.
(författare)
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Evaluation of satellite based indices for gross primary production estimates in a sparse savanna in the Sudan
- 2009
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4189. ; 6:1, s. 129-138
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Tidskriftsartikel (refereegranskat)abstract
- One of the more frequently applied methods for integrating controls on primary production through satellite data is the Light Use Efficiency (LUE) approach. Satellite indices such as the Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI) and the Shortwave Infrared Water Stress Index (SIWSI) have previously shown promise as predictors of primary production in several different environments. In this study, we evaluate NDVI, EVI and SIWSI derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite sensor against in-situ measurements from central Sudan in order to asses their applicability in LUE-based primary production modeling within a water limited environment. Results show a strong correlation between vegetation indices and gross primary production (GPP), demonstrating the significance of vegetation indices for deriving information on primary production with relatively high accuracy at similar areas. Evaluation of SIWSI however, reveal that the fraction of vegetation apparently is to low for the index to provide accurate information on canopy water content, indicating that the use of SIWSI as a predictor of water stress in satellite data-driven primary production modeling in similar semi-arid ecosystems is limited.
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| 53. |
- Sjöström, Martin, et al.
(författare)
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Exploring the potential of MODIS EVI for modeling gross primary production across African ecosystems
- 2011
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Ingår i: Remote Sensing of Environment. - : Elsevier BV. - 0034-4257. ; 115:4, s. 1081-1089
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Tidskriftsartikel (refereegranskat)abstract
- One of the most frequently applied methods for integrating controls on primary production through satellite data is the light use efficiency (LUE) approach, which links vegetation gross or net primary productivity (GPP or NPP) to remotely-sensed estimates of absorbed photosynthetically active radiation (APAR). Eddy covariance towers provide continuous measurements of carbon flux, presenting an opportunity for evaluation of satellite estimates of GPP. Here we investigate relationships between eddy covariance estimated GPP, environmental variables and the enhanced vegetation index (EVI) from the Moderate Resolution Imaging Spectroradiometer (MODIS) across African savanna ecosystems. EVI was found to correlate well with estimated GPP on a site-by-site basis. Combining EVI with tower-measured PAR and evaporative fraction (EF, a measure of water sufficiency) improved the direct relationship between GPP and EVI at the majority of the sites. The slope of this relationship was strongly related to site peak leaf area index (LAI). These results are promising for the extension of GPP through the use of remote sensing data to a regional or even continental scale.
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| 54. |
- Sjöström, Martin, et al.
(författare)
-
Expression of HGF, pMet, and pAkt is related to benefit of radiotherapy after breast-conserving surgery : a long-term follow-up of the SweBCG91-RT randomised trial
- 2020
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Ingår i: Molecular Oncology. - : Wiley. - 1574-7891 .- 1878-0261. ; 14:11, s. 2713-2726
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Tidskriftsartikel (refereegranskat)abstract
- Experimental studies suggest that hepatocyte growth factor (HGF) and its transmembrane tyrosine kinase receptor, Met, in part also relying on Akt kinase activity, mediate radioresistance. We investigated the importance of these biomarkers for the risk of ipsilateral breast tumour recurrence (IBTR) after adjuvant radiotherapy (RT) in primary breast cancer. HGF, phosphorylated Met (pMet) and phosphorylated Akt (pAkt) were evaluated immunohistochemically on tissue microarrays from 1004 patients in the SweBCG91-RT trial, which randomly assigned patients to breast-conserving therapy, with or without adjuvant RT. HGF was evaluated in the stroma (HGFstr); pMet in the membrane (pMetmem); HGF, pMet and pAkt in the cytoplasm (HGFcyt, pMetcyt, pAktcyt); and pAkt in the nucleus (pAktnuc). The prognostic and treatment predictive effects were evaluated to primary endpoint IBTR as first event during the first 5 years. Patients with tumours expressing low levels of HGFcyt and pMetcyt and high levels of pAktnuc derived a larger benefit from RT [hazard ratio (HR): 0.11 (0.037–0.30), 0.066 (0.016–0.28) and 0.094 (0.028–0.31), respectively] compared to patients with high expression of HGFcyt and pMetcyt, and low pAktnuc [HR: 0.36 (0.19–0.67), 0.35 (0.20–0.64) and 0.47 (0.32–0.71), respectively; interaction analyses: P = 0.052, 0.035 and 0.013, respectively]. These differences remained in multivariable analysis when adjusting for patient age, tumour size, histological grade, St Gallen subtype and systemic treatment (interaction analysis, P-values: 0.085, 0.027, and 0.023, respectively). This study suggests that patients with immunohistochemically low HGFcyt, low pMetcyt and high pAktnuc may derive an increased benefit from RT after breast-conserving surgery concerning the risk of developing IBTR.
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| 55. |
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| 56. |
- Sjöström, Martin, et al.
(författare)
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Identification and validation of single-sample breast cancer radiosensitivity gene expression predictors
- 2018
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Ingår i: Breast Cancer Research. - : Springer Science and Business Media LLC. - 1465-5411 .- 1465-542X. ; 20:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Adjuvant radiotherapy is the standard of care after breast-conserving surgery for primary breast cancer, despite a majority of patients being over- or under-treated. In contrast to adjuvant endocrine therapy and chemotherapy, no diagnostic tests are in clinical use that can stratify patients for adjuvant radiotherapy. This study presents the development and validation of a targeted gene expression assay to predict the risk of ipsilateral breast tumor recurrence and response to adjuvant radiotherapy after breast-conserving surgery in primary breast cancer. Methods: Fresh-frozen primary tumors from 336 patients radically (clear margins) operated on with breast-conserving surgery with or without radiotherapy were collected. Patients were split into a discovery cohort (N = 172) and a validation cohort (N = 164). Genes predicting ipsilateral breast tumor recurrence in an Illumina HT12 v4 whole transcriptome analysis were combined with genes identified in the literature (248 genes in total) to develop a targeted radiosensitivity assay on the Nanostring nCounter platform. Single-sample predictors for ipsilateral breast tumor recurrence based on a k-top scoring pairs algorithm were trained, stratified for estrogen receptor (ER) status and radiotherapy. Two previously published profiles, the radiosensitivity signature of Speers et al., and the 10-gene signature of Eschrich et al., were also included in the targeted panel. Results: Derived single-sample predictors were prognostic for ipsilateral breast tumor recurrence in radiotherapy-treated ER+ patients (AUC 0.67, p = 0.01), ER+ patients without radiotherapy (AUC = 0.89, p = 0.02), and radiotherapy-treated ER- patients (AUC = 0.78, p < 0.001). Among ER+ patients, radiotherapy had an excellent effect on tumors classified as radiosensitive (p < 0.001), while radiotherapy had no effect on tumors classified as radioresistant (p = 0.36) and there was a high risk of ipsilateral breast tumor recurrence (55% at 10 years). Our single-sample predictors developed in ER+ tumors and the radiosensitivity signature correlated with proliferation, while single-sample predictors developed in ER- tumors correlated with immune response. The 10-gene signature negatively correlated with both proliferation and immune response. Conclusions: Our targeted single-sample predictors were prognostic for ipsilateral breast tumor recurrence and have the potential to stratify patients for adjuvant radiotherapy. The correlation of models with biology may explain the different performance in subgroups of breast cancer.
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| 57. |
- Sjöström, Martin, et al.
(författare)
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Lack of G protein-coupled estrogen receptor (GPER) in the plasma membrane is associated with excellent long-term prognosis in breast cancer
- 2014
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Ingår i: Breast Cancer Research and Treatment. - : Springer Verlag (Germany). - 0167-6806 .- 1573-7217. ; 145:1, s. 61-71
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Tidskriftsartikel (refereegranskat)abstract
- G protein-coupled estrogen receptor (GPER), or GPR30, is a membrane receptor reported to mediate non-genomic estrogen responses. Tamoxifen is a partial agonist at GPER in vitro. Here, we investigated if GPER expression is prognostic in primary breast cancer, if the receptor is treatment-predictive for adjuvant tamoxifen, and if receptor subcellular localization has any impact on the prognostic value. Total and plasma membrane (PM) GPER expression was analyzed by immunohistochemistry in breast tumors from 742 postmenopausal lymph node-negative patients subsequently randomized for tamoxifen treatment for 2-5 years versus no systemic treatment, regardless of estrogen receptor (ER) status, and with a median follow-up of 17 years for patients free of event. PM GPER expression was a strong independent prognostic factor for poor prognosis in breast cancer without treatment-predictive information for tamoxifen. In the tamoxifen-treated ER-positive and progesterone receptor (PgR)-positive patient subgroup, the absence of PM GPER (53 % of all ER-positive tumors) predicted 91 % 20-year distant disease-free survival, compared to 73 % in the presence of GPER (p = 0.001). Total GPER expression showed positive correlations with ER and PgR and negative correlation with histological grade, but the correlations were biphasic. On the other hand, PM GPER expression showed strong negative correlations with ER and PgR, and strong positive correlation with HER2 overexpression and high histological grade. GPER overexpression and PM localization are critical events in breast cancer progression, and lack of GPER in the PM is associated with excellent long-term prognosis in ER-positive and PgR-positive tamoxifen-treated primary breast cancer.
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| 58. |
- Sjöström, Mats, et al.
(författare)
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Mandibular resection in patients with head and neck cancer : acute and long-term complications after reconstruction
- 2022
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Ingår i: Acta Oto-Laryngologica. - : Taylor & Francis Group. - 0001-6489 .- 1651-2251. ; 142:1, s. 78-83
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Tidskriftsartikel (refereegranskat)abstract
- Background: The treatment of head and neck cancer is an intensive multimodal treatment that has a great impact on the individual patient.Aims/Objectives: This study aimed to evaluate acute and long-term complications associated with mandibular resections and reconstructions.Material and Methods: We retrospectively retrieved data on complications and recurrences among patients that underwent mandibular resections and reconstructions for treating oral cavity cancer (n = 190 patients) and osteoradionecrosis (ORN, n = 72). Reconstructions included composite grafts (n = 177), soft tissue flaps (n = 61), or primary closure without any graft (n = 24).Results: Forty-two patients that underwent reconstructions with composite grafts displayed serious complications (Clavien–Dindo ≥ IIIa). The complication rates were similar between patients treated for oral cavity cancer and patients treated for ORN. Patients that underwent a primary closure without any graft, had a significantly lower risk of complications compared to patients that underwent the other treatments. After hospitalization, 181 patients (69%) had at least one complication.Conclusions: A majority of patients undergoing resection and reconstruction due to oral cancer/ORN suffered from postoperative complications regardless of indication, comorbidity status or reconstruction technique. The risk of Clavien–Dindo grade IIIa–V events was significantly lower for patients treated with primary closure without grafts. Significance: The results from this study clarifies the importance of in-depth analyse prior to decision of treatment for patients with head and neck cancer.
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| 59. |
- Sjöström, Magnus, et al.
(författare)
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Orbit Feedback System for the MAX IV 3 GeV Storage Ring
- 2011
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Ingår i: [Host publication title missing]. - 9789290833666 ; , s. 499-501
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Konferensbidrag (refereegranskat)abstract
- The paper gives an overview of the planned orbit correc- tion system for the 3 GeV storage ring at the MAX IV lab- oratory, a light source facility currently under construction in Lund, Sweden[1, 2]. The ring will have a vertical beam size in the 1-4μm range in the insertion device (ID) straight sections depending on coupling[3], which places high re- quirements on the orbit stability. To meet this the ring will be equipped with 200 beam position monitors (BPMs) and two different sets of corrector magnets, which will be used by two separate orbit feedback loops; a slow orbit feedback (SOFB) loop to handle misalignments and drifts and a fast orbit feedback (FOFB) loop to reduce beam jitter. The pa- per also includes a brief description of the various engi- neering boundary conditions on the orbit feedback design for the MAX IV 3 GeV storage ring.
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| 60. |
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