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- Edström-Hägerwall, Anneli, et al.
(författare)
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Alpha-1-microglobulin protects from heme induced placenta and kidney damage in a pregnant ewe model for preeclampsia
- 2013
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Ingår i: Pregnancy Hypertension. - : Elsevier BV. - 2210-7789. ; 3:2, s. 1-70
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Konferensbidrag (refereegranskat)abstract
- INTRODUCTION: Previous gene expression analysis have identified fetal hemoglobin (HbF) as a plausible etiological factor in preeclampsia. Free hemoglobin and its degradation products, e.g. heme, are known to cause oxidative stress, tissue damage, and vaso-constriction, typical findings in preeclampsia.OBJECTIVE: To study alpha-1-microglobulin (A1M), an endogenous radical scavenger and heme-binder, as a potential treatment for preeclampsia using the pregnant ewe preeclampsia model. Free Hb and heme are known to take part in the pathology of this model and therefor well suited for evaluation of recombinant A1M as a therapy.METHODS: 11 pregnant ewes, at gestational age 125-131 days, were acclimatized for 36h and then starved for another 36h to induce preeclampsia symptoms. At the end of starvation period, they were treated either with placebo (n=6) or A1M injections (n=5). After injections, food was re-introduced and ewes further followed for 72h. The ewes were sacrificed the 6th day after beginning of acclimatization. Throughout the 6 days, the animals were monitored for blood pressure and different blood and urine parameters. Whole blood, kidney and placenta tissue samples were collected from the ewes. Gene expression analysis, blood analysis, histology and electron microscopy were used to evaluate the therapeutic effects of A1M.RESULTS: Starvation increased the amount of free heme in the blood. The ultrastructure of the placenta and kidney were damaged in a way similar to what previously have been described for PE. The glomeruli and the tubuli were damaged which was reflected by increased Ficol clearance and increased plasma creatinine levels. Treatment with A1M significantly normalized the kidney functions. The most profound changes on gene expression level were found in white blood cells in the starved animals. Starvation decreases mRNA expression for anti-oxidants such as CAT (P=0.04), SOD1 (P=0.008), SOD2 (1.8-fold) as well as angiogenetic factors such as VEGF (P=0.02) and HGF (1.6-fold). A1M treatment rescued the decreased expression of SOD2 (P=0.04) and HGF (2-fold).CONCLUSION: A1M is well tolerated and shows high potential as a treatment for PE-like symptoms in the pregnant ewe model for PE.
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| 2. |
- Edström, Lena, 1978-
(författare)
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Adsorption Studies with Liquid Chromatography : Experimental Preparations for Thorough Determination of Adsorption Data
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Analytical chemistry is a field with a vast variety of applications. A robust companion in the field is liquid chromatography, the method used in this thesis, which is an established workhorse and a versatile tool in many different disciplines. It can be used for identification and quantification of interesting compounds generally present in low concentrations, called analytical scale chromatography. It can also be used for isolation and purification of high value compounds, called preparative chromatography. The latter is usually conducted in large scale with high concentrations. With high concentrations it is also possible to determine something called adsorption isotherms.Determination of adsorption isotherms is a useful tool for quite a wide variety of reasons. It can be used for characterisation of chromatographic separation systems, and then gives information on the retention mechanism as well as provides the possibility to study column-column and batch-batch reproducibility. If a protein is immobilised on a solid support, adsorption isotherms can be used for pharmacological characterisation of drug-protein interactions. Moreover, they can be used for the study of unexpected chromatographic phenomena.If the adsorption isotherm is known it is also possible to simulate chromatograms, and subsequently optimise the separation process numerically. The gain of a numerically optimised separation process is higher purity or yield of valuable compounds such as pharmaceuticals or antioxidants, as well as reducing the solvent usage. Taken all together, it saves time, money and the environment.However, the process of the adsorption isotherm determination requires a number of careful experimental considerations and preparations, and these are the main focus of the thesis. Important steps along the way include the choice of separation system and of suitable analytes, preparation of mobile phases and sample solutions, calibration, determination of injection profiles and column void, and of course the adsorption isotherm determination method itself. It is also important to keep track of parameters such as temperature and pH. These issues are discussed in this thesis.At the end, a description of useful methods for processing of the raw adsorption isotherm data is presented, as well as a brief passage on methods for numerical optimisation.
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| 6. |
- Fornstedt, Torgny, et al.
(författare)
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Deformations of overloaded bands under pH-stable conditions in reversed phase chromatography
- 2011
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Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673 .- 1873-3778. ; 1218:15, s. 1966-1973
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Tidskriftsartikel (refereegranskat)abstract
- It has recently been demonstrated, using mathematical models, how peculiar overloaded band profiles of basic compounds are due to the local pH in the column when using low capacity buffers. In this study, overloaded peak shapes resulting after injection of carefully pH matched samples close to the pKa of the chosen solute are investigated primarily on two columns; one hybrid silica C18 column (Kromasil Eternity) and one purely polymeric column (PLRP-S), the latter lacking C18 ligands. It was found that distorted peaks of the basic test compound appear even though there is no difference in pH between the injected sample solution and the eluent; the previous explanation to why these effects occur is based on a pH mismatch. Thus, the unusual band shapes are not due to an initial pH difference. Furthermore, it was observed that the effect does not appear on polymeric columns without C18 ligands, but only on columns with C18 ligands, independently of the base matrix (silica, hybrid silica, polymeric)
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| 7. |
- Fornstedt, Torgny, 1957-, et al.
(författare)
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Injection profiles in liquid chromatography. I. A fundamental investigation
- 2010
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Ingår i: Journal of Chromatography A. - Amsterdam : Elsevier. - 0021-9673 .- 1873-3778. ; 1217:26, s. 4306-4312
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Tidskriftsartikel (refereegranskat)abstract
- This is a fundamental experimental and theoretical investigation on how the injection profile depends on important experimental parameters. The experiments revealed that the injection profile becomes more eroded with increased (i) flow rate, (ii) viscosity of the eluent, (iii) size of the solute, (iv) injection volume and (v) inner diameter of the injection loop capillary. These observations cannot be explained by a 1D-convection-diffusion equation, since it does not account for the effect of the parabolic flow and the radial diffusion on the elution profile. Therefore, the 1D model was expanded into a 2D-convection-diffusion equation with cylindrical coordinates, a model that showed a good agreement with the experimental injection profiles dependence on the experimental parameters. For a deeper understanding of the appearance of the injection profile the 2D model is excellent, but to account for injection profiles of various injection volumes and flow rates in preparative and process-chromatography using computer-optimizations, a more pragmatic approach must be developed. The result will give guidelines about how to reduce the extra-column variance caused by the injection profile. This is important both for preparative and analytical chromatography; in particular for modern analytical systems using short and narrow columns
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| 8. |
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| 9. |
- Fornstedt, Torgny, et al.
(författare)
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Why UHPLC Produces More Tailing Peaks Than HPLC, Why it Does Not Matter and How it Can be Addressed
- 2012
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Konferensbidrag (refereegranskat)abstract
- The purpose of this study is to demonstrate, with experiments and with computer simulations based on a firm chromatographic theory, that the wide spread perception of that the United States Pharmacopeia tailing factor must be lower than 2 (Tf < 2) is questionable when using the latest generation of LC equipment. It is shown that highly efficient LC separations like those obtained with sub-2 ÎŒm porous and 2.7 ÎŒm superficially porous particles (UHPLC) produce significantly higher Tf -values than the corresponding separation based on 3 ÎŒm porous particles (HPLC) when the same amount of sample is injected. Still UHPLC separations provide a better resolution to adjacent peaks. Expressions have been derived that describe how the Tf-value changes with particle size or number of theoretical plates. Expressions have also been derived that can be used to scale the injection volume based on particle size or number of theoretical plates to maintain the Tf-value when translating a HPLC separation to the corresponding UHPLC separation. An aspect that has been ignored in previous publications. Finally, data obtained from columns with different age/condition indicate that Tf-values should be complemented by a peak width measure to provide a more objective quality measure.
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| 10. |
- Forssén, Patrik, 1966-, et al.
(författare)
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Injection profiles in liquid chromatography II : Predicting accurate injection-profiles for computer-assisted preparative optimizations
- 2011
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Ingår i: Journal of Chromatography A. - Amsterdam : Elsevier. - 0021-9673 .- 1873-3778. ; 1218:34, s. 5794-5800
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Tidskriftsartikel (refereegranskat)abstract
- In computer assisted optimization of liquid chromatography it has been known for some years that it is important to use experimental injection profiles, instead of rectangular ones, in order to calculate accurate elution bands. However, the incorrectly assumed rectangular profiles are still mostly used especially in numerical optimizations. The reason is that the acquisition of injection profiles, for each injection volume and each flow rate considered in a computer-assisted optimization requires a too large number of experiments. In this article a new function is proposed, which enables highly accurate predictions of the injection profiles and thus more accurate computer optimizations, with a minimum experimental effort. To model the injection profiles for any injection volume at a constant flow rate, as few as two experimental injection profiles are required. If it is desirable to also take the effect of flow rate on the injection profiles into account, then just two additional experiments are required. The overlap between fitted and experimental injection profiles at different flow rates and different injection volumes were excellent, more than 90%, using experimental injection profiles from just four different injection volumes at two different flow rates. Moreover, it was demonstrated that the flow rate has a minor influence on the injection profiles and that the injection volume is the main parameter that needs to be accounted for.
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