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- Bouksila, Fethi
(författare)
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Sustainability of irrigated agriculture under salinity pressure – A study in semiarid Tunisia
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In semiarid and arid Tunisia, water quality and agricultural practices are the major contributing factors to the degradation of soil resources threatening the sustainability of irrigation systems and agricultural productivity. Nowadays, about 50% of the total irrigated areas in Tunisia are considered at high risk for salinization. The aim of this thesis was to study soil management and salinity relationships in order to assure sustainable irrigated agriculture in areas under salinity pressure. To prevent further soil degradation, farmers and rural development officers need guidance and better tools for the measurement, prediction, and monitoring of soil salinity at different observation scales, and associated agronomical strategy. Field experiments were performed in semi-arid Nabeul (sandy soil), semi-arid Kalâat Landalous (clay soil), and the desertic Fatnassa oasis (gypsiferous soil). The longest observation period represented 17 years. Besides field studies, laboratory experiments were used to develop accurate soil salinity measurements and prediction techniques. In saline gypsiferous soil, the WET sensor can give similar accuracy of soil salinity as the TDR if calibrated values of the soil parameters are used instead of standard values. At the Fatnassa oasis scale, the predicted values of ECe and depth of shallow groundwater Dgw using electromagnetic induction EM-38 were found to be in agreement with observed values with acceptable accuracy. At Kalâat Landalous (1400 ha), the applicability of artificial neural network (ANN) models for predicting the spatial soil salinity (ECe) was found to be better than multivariate linear regression (MLR) models. In semi-arid and desertic Tunisia, irrigation and drainage reduce soil salinity and dilute the shallow groundwater. However, the ECgw has a larger impact than soil salinity variation on salt balance. Based on the findings related to variation in the spatial and temporal soil and groundwater properties, soil salinization factors were identified and the level of soil “salinization risk unit” (SRU) was developed. The groundwater properties, especially the Dgw, could be considered as the main cause of soil salinization risk in arid Tunisia. However, under an efficient drainage network and water management, the soil salinization could be considered as a reversible process. The SRU mapping can be used by both land planners and farmers to make appropriate decisions related to crop production and soil and water management.
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- Cárdenas-Jaén, Karina, et al.
(författare)
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Chronic use of statins and acetylsalicylic acid and incidence of post-endoscopic retrograde cholangiopancreatography acute pancreatitis : A multicenter, prospective, cohort study
- 2021
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Ingår i: Digestive Endoscopy. - : Wiley-Blackwell. - 0915-5635 .- 1443-1661. ; 33:4, s. 639-647
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Post-endoscopic retrograde cholangiopancreatography (ERCP) acute pancreatitis (PEP) is a frequent complication of this endoscopic procedure. Chronic statin intake has been linked to lower incidence and severity of acute pancreatitis (AP). Periprocedural rectal administration of non-steroidal anti-inflammatory drugs is protective against PEP, but the role of chronic acetylsalicylic acid (ASA) treatment is unclear. We aimed to investigate whether statins and chronic ASA intake are associated with lower risk of PEP.METHODS: An international, multicenter, prospective cohort study. Consecutive patients undergoing ERCP in seven European centers were included. Patients were followed-up to detect those with PEP. Multivariate analysis by means of binary logistic regression was performed, and adjusted odds ratios (aORs) were calculated.RESULTS: A total of 1150 patients were included, and 70 (6.1%) patients developed PEP. Among statins users, 8.1% developed PEP vs. 5.4% among non-users (P = 0.09). Multivariate analysis showed no association between statin use and PEP incidence (aOR 1.68 (95% CI 0.94-2.99, P = 0.08)). Statin use had no effect on severity of PEP, being mild in 92.0% of statin users vs. 82.2% in non-statin users (P = 0.31). Chronic ASA use was not associated with PEP either (aOR 1.02 (95% CI 0.49-2.13), P = 0.96). Abuse of alcohol and previous endoscopic biliary sphincterotomy were protective factors against PEP, while >1 pancreatic guidewire passage, normal bilirubin values, and duration of the procedure >20 minutes, were risk factors.CONCLUSIONS: The use of statins or ASA is not associated with a lower risk or a milder course of PEP.
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- Cárdenas, Marité, et al.
(författare)
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Structure of DNA-Cationic Surfactant Complexes at Hydrophobically Modified and Hydrophilic Silica Surfaces as Revealed by Neutron Reflectometry
- 2011
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 27:20, s. 12506-12514
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Tidskriftsartikel (refereegranskat)abstract
- In this article, we discuss the structure and composition of mixed DNA-cationic surfactant adsorption layers on both hydrophobic and hydrophilic solid surfaces. We have focused on the effects of the bulk concentrations, the surfactant chain length, and the type solid surface on the interfacial layer structure (the location, coverage, and conformation the e DNA and surfactant molecules). Neutron reflectometry is the technique of choice for revealing the surface layer structure by means of selective deuteration. We start by studying the interfacial complexation of DNA with dodecyltrimethylammonium bromide (DTAB) and hexadecyltrimethylammonium bromide (CTAB) on hydrophobic surfaces, where we show that DNA molecules are located on top of a self-assembled surfactant monolayer, with the thickness of the DNA layer and the surfactant DNA ratio determined by the surface coverage of the underlying cationic layer. The surface coverages of surfactant and DNA are determined by the bulk concentration of the surfactant relative to its critical micelle concentration (cmc). The structure of the interfacial layer is not affected by the choice of cationic surfactant studied. However, to obtain similar interfacial structures, a higher concentration in relation to its cmc is required for the more soluble DTAB surfactant with a shorter alkyl chain than for CTAB. Our results suggest that the DNA Molecules Will spontaneously form a relatively dense, thin layer on top of a surfactant monolayer (hydrophobic surface) or a layer of admicelles (hydrophilic surface) as long as the surface concentration of surfactant is great enough to ensure a high interfacial-charge density. These findings have implications for bioanalytical and nanotechnology applications, which require the deposition of DNA layers with well controlled structure and composition.
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- Hedström, Gustaf
(författare)
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Prognostic Markers in Diffuse Large B-cell Lymphoma : How Bad can it be
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Diffuse large B-cell lymphoma (DLBCL), which is the most common type of lymphoma, is characterised by its aggressiveness and poor outcome without adequate treatment and also for its biological and clinical heterogeneity. It is therefore highly desirable to gain a more profound understanding of the underlying biology of the disease, as well as predictive factors for the guidance of treatment. The studies presented here attempt to gain an overall grasp on DLBCL, from the epidemiological level down to the genomic level.The tumour microenvironment consists of both tumour cells and normal infiltrating cells in a delicate interplay. By assessing the number of infiltrating mast cells (MCs) in the microenvironment, a correlation between low numbers of MCs and poorer prognosis of DLBCL was found.However, malignant cells are not only affected by environmental conditions but also by intrinsic factors, such as small non-coding microRNAs. A low expression level of microRNA-129 was found to correlate with poor survival of DLBCL and the finding remained significant even for rituximab-treated patients.An even smaller intracellular genomic unit is one single nucleotide. The single nucleotide polymorphism 309 (SNP309) is a T to G change in the promotor region of MDM2, a regulatory protein in the p53 pathway, which results in increased transcription of MDM2 and thus decreased levels of p53. It was found that homozygous T allele patients had longer overall survival, as well as disease-specific survival and disease-free survival. However, treatment with rituximab eliminated the predictive value of the SNP309 polymorphism.In the last project presented in this thesis we used epidemiological methods to analyse all DLBCL cases diagnosed 2000-2013 in Sweden. Here it was possible to categorically show that higher age is an adverse prognostic factor, and most importantly, this starts from a young age.In conclusion, within this thesis I have applied different laboratory and analysis techniques to examine DLBCL biology in relation to the clinic. I have identified potential new prognostic markers, contributed to an enhanced understanding of DLBCL biology and described epidemiological data from one of the largest DLBCL cohorts ever presented. All of these aspects provide important information for a deeper understanding of the disease DLBCL.
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- Hedström, Jonas, et al.
(författare)
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Cholecystectomy After Previous Bariatric Surgery with Special Focus on Pregnant Patients—Results from Two Large Nationwide Registries
- 2020
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Ingår i: Obesity Surgery. - : Springer Science and Business Media LLC. - 0960-8923 .- 1708-0428. ; 30:5, s. 1874-1880
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Tidskriftsartikel (refereegranskat)abstract
- Background: Biliary complications during pregnancy is an important issue. The aim of this study was to examine if there is an increased risk to perform cholecystectomy during pregnancy in patients with previous bariatric surgery in comparison to other females subjected to cholecystectomy. Methods: The Nationwide Swedish Registry for Gallstone Surgery (GallRiks) and the Scandinavian Obesity Surgery Registry (SOReg) were combined. Female patients 18–45 years old were included. The study group was patients with a history of bariatric surgery whom were pregnant at the time of cholecystectomy. This group was compared with pregnant patients without previous bariatric surgery and non-pregnant with and without previous bariatric surgery. Results: In total, 21,314 patients were included and 292 underwent surgery during pregnancy. From 1282 patients identified in both registers, 16 patients were pregnant at the time of cholecystectomy. Acute cholecystectomy was performed in 5922 (28%) non-pregnant and 199 (68%) pregnant (p < 0.001), including 11/16 (69%) pregnant with previous bariatric surgery. When comparing all pregnant patients, those with previous bariatric surgery had longer operative time (p = 0.031) and length of stay (p = 0.043), but no differences were seen when only comparing patients with an acute indication for surgery. There was no difference in complications comparing pregnant patients with previous bariatric surgery with non-pregnant, both with and without previous bariatric surgery. Conclusions: Cholecystectomy during pregnancy in patients with previous bariatric surgery seems to be safe. The increased risk seen in the non-pregnant group after previous bariatric surgery is not seen in pregnancy, possibly due to an optimization of the circumstances at surgery.
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