| 1. |
|
|
| 2. |
|
|
| 3. |
- Dupont, Chris L., et al.
(författare)
-
Functional Tradeoffs Underpin Salinity-Driven Divergence in Microbial Community Composition
- 2014
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:2, s. e89549-
-
Tidskriftsartikel (refereegranskat)abstract
- Bacterial community composition and functional potential change subtly across gradients in the surface ocean. In contrast, while there are significant phylogenetic divergences between communities from freshwater and marine habitats, the underlying mechanisms to this phylogenetic structuring yet remain unknown. We hypothesized that the functional potential of natural bacterial communities is linked to this striking divide between microbiomes. To test this hypothesis, metagenomic sequencing of microbial communities along a 1,800 km transect in the Baltic Sea area, encompassing a continuous natural salinity gradient from limnic to fully marine conditions, was explored. Multivariate statistical analyses showed that salinity is the main determinant of dramatic changes in microbial community composition, but also of large scale changes in core metabolic functions of bacteria. Strikingly, genetically and metabolically different pathways for key metabolic processes, such as respiration, biosynthesis of quinones and isoprenoids, glycolysis and osmolyte transport, were differentially abundant at high and low salinities. These shifts in functional capacities were observed at multiple taxonomic levels and within dominant bacterial phyla, while bacteria, such as SAR11, were able to adapt to the entire salinity gradient. We propose that the large differences in central metabolism required at high and low salinities dictate the striking divide between freshwater and marine microbiomes, and that the ability to inhabit different salinity regimes evolved early during bacterial phylogenetic differentiation. These findings significantly advance our understanding of microbial distributions and stress the need to incorporate salinity in future climate change models that predict increased levels of precipitation and a reduction in salinity.
|
|
| 4. |
- Emanuel, Robyn M, et al.
(författare)
-
Myeloproliferative Neoplasm (MPN) Symptom Assessment Form Total Symptom Score : Prospective International Assessment of an Abbreviated Symptom Burden Scoring System Among Patients With MPNs
- 2012
-
Ingår i: Journal of Clinical Oncology. - 0732-183X .- 1527-7755. ; 30:33, s. 4098-4103
-
Tidskriftsartikel (refereegranskat)abstract
- PURPOSE Myeloproliferative neoplasm (MPN) symptoms are troublesome to patients, and alleviation of this burden represents a paramount treatment objective in the development of MPN-directed therapies. We aimed to assess the utility of an abbreviated symptom score for the most pertinent and representative MPN symptoms for subsequent serial use in assessing response to therapy.PATIENTS AND METHODSThe Myeloproliferative Neoplasm Symptom Assessment Form total symptom score (MPN-SAF TSS) was calculated as the mean score for 10 items from two previously validated scoring systems. Questions focus on fatigue, concentration, early satiety, inactivity, night sweats, itching, bone pain, abdominal discomfort, weight loss, and fevers.RESULTS MPN-SAF TSS was calculable for 1,408 of 1,433 patients with MPNs who had a mean score of 21.2 (standard deviation [SD], 16.3). MPN-SAF TSS results significantly differed among MPN disease subtypes (P < .001), with a mean of 18.7 (SD, 15.3), 21.8 (SD, 16.3), and 25.3 (SD, 17.2) for patients with essential thrombocythemia, polycythemia vera, and myelofibrosis, respectively. The MPN-SAF TSS strongly correlated with overall quality of life (QOL; r = 0.59; P < .001) and European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire C30 (EORTC QLQ-C30) functional scales (all P < .001 and absolute r ≥ 0.50 except social functioning r = 0.48). No significant trends were present when comparing therapy subgroups. The MPN-SAF TSS had excellent internal consistency (Cronbach's α = .83). Factor analysis identified a single underlying construct, indicating that the MPN-SAF TSS is an appropriate, unified scoring method.CONCLUSIONThe MPN-SAF TSS is a concise, valid, and accurate assessment of MPN symptom burden with demonstrated clinical utility in the largest prospective MPN symptom study to date. This new prospective scoring method may be used to assess MPN symptom burden in both clinical practice and trial settings.
|
|
| 5. |
- Enmark, Martin, et al.
(författare)
-
A Deeper Investigation of Strange Preparative Band Shapes of a Simple Racemic Solute on tris-(3, 5- dimethylphenyl)carbamoyl Cellulose as Chiral Stationary Phase
- 2011
-
Konferensbidrag (refereegranskat)abstract
- The adsorption equilibria of racemic methyl mandelate on a tris-(3, 5-dimethylphenyl)carbamoyl cellulose chiral stationary phase (CSP) has a peculiar behavior. The preparative band shape of the more retained enantiomer was very unusual with an inflection point at low concentrations whereas the less retained enantiomer shows normal type I adsorption behavior. For a deeper understanding of this separation adsorption isotherms were determined and further analyzed with Scatchard plots combined with adsorption energy distribution calculations. The less retained enantiomer was best described by Tóth adsorption isotherm while the second enantiomer was best described with a bi-Moreau adsorption isotherm. The Moreau model is an extension of the Langmuir model including non-ideal adsorbate-adsorbate interactions; here the unusual model provided an explanation to the non-ideal adsorption of the more retained enantiomer. Furthermore, the possibility of using the Moreau model as a local model for adsorption in AED calculations was evaluated by synthetically generated raw adsorption slope data. It was demonstrated that the AED accurately could predict the number of adsorption sites for the generated data. The adsorption behavior of both enantiomers was also studied at several different temperatures and it was found to be exothermic; in addition, the non-ideal adsorbate-adsorbate interaction strength decreases with increasing temperature. Stochastic analysis of the adsorption process could identify a single kinetic site for each enantiomer. The average amount of adsorption/desorption events increases and the sojourn time decreases with increasing temperature
|
|
| 6. |
- Enmark, Martin, et al.
(författare)
-
A Deeper Understanding of a Complex Adsorption Behavior in a Common Chiral, Separation System
- 2011
-
Konferensbidrag (refereegranskat)abstract
- The adsorption equilibria of racemic methyl mandelate on a tris-(3,5-dimethylphenyl)carbamoyl cellulose chiral stationary phase (CSP) was investigated. This separation has previously been performed and analyzed on a methylcellulose tribenzoate coated CSP. In that case, both enantiomers could be described with a bi-Langmuir adsorption isotherm, convex upwards (type I). In our case, two fundamentally different properties were observed. First, the elution order was reversed. Furthermore, only the less retained enantiomer shows type I adsorption behavior, while the adsorption isotherm of the more retained compound contained an inflection point at low concentration. To analyze these differences, adsorption isotherms were determined and further analyzed using Scatchard plots and adsorption energy distribution calculations. The less retained enantiomer was best described by Tóth adsorption isotherm while the second enantiomer was best described with a bi-Moreau adsorption isotherm. The Moreau model is an extension of the Langmuir model including non-ideal adsorbate-adsorbate interactions; here the unusual model provided an explanation to the non-ideal adsorption of the more retained enantiomer. Furthermore, the possibility of using the Moreau model as a local model for adsorption in AED calculations was evaluated by synthetically generated raw adsorption slope data. It was demonstrated that the AED accurately could predict the number of adsorption sites for the generated data. The adsorption behavior of both enantiomers was also studied at several different temperatures and it was found to be exothermic; in addition, the non-idealadsorbate-adsorbate interaction strength decreases with increasing temperature. Stochastic analysis of the adsorption process could identify a single kinetic site for each enantiomer. The average amount of adsorption/desorption events increases and the sojourn time decreases with increasing temperature.
|
|
| 7. |
- Enmark, Martin, et al.
(författare)
-
A systematic investigation of algorithm impact in preparative chromatography with experimental verifications
- 2011
-
Ingår i: Journal of Chromatography A. - Amsterdam : Elsevier. - 0021-9673 .- 1873-3778. ; 1218:5, s. 662-672
-
Tidskriftsartikel (refereegranskat)abstract
- Computer-assisted optimization of chromatographic separations requires finding the numerical solution of the Equilibrium-Dispersive (ED) mass balance equation. Furthermore, the competitive adsorption isotherms needed for optimization are often estimated numerically using the inverse method that also solves the ED equations. This means that the accuracy of the estimated adsorption isotherm parameters explicitly depends on the numerical accuracy of the algorithm that is used to solve the ED equations. The fast and commonly used algorithm for this purpose, the Rouchon Finite Difference (RFD) algorithm, has often been reported not to be able to accurately solve the ED equations for all practical preparative experimental conditions, but its limitations has never been completely and systematically investigated. In this study, we thoroughly investigate three different algorithms used to solve the ED equations: the RFD algorithm, the Orthogonal Collocation on Finite Elements (OCFE) method and a Central Difference Method (CDM) algorithm, both for increased theoretical understanding and for real cases of industrial interest. We identified discrepancies between the conventional RFD algorithm and the more accurate OCFE and CDM algorithms for several conditions, such as low efficiency, increasing number of simulated components and components present at different concentrations. Given high enough efficiency, we experimentally demonstrate good prediction of experimental data of a quaternary separation problem using either algorithm, but better prediction using OCFE/CDM for a binary low efficiency separation problem or separations when the compounds have different efficiency. Our conclusion is to use the RFD algorithm with caution when such conditions are present and that the rule of thumb that the number of theoretical plates should be greater than 1000 for application of the RFD algorithm is underestimated in many cases
|
|
| 8. |
- Enmark, Martin, et al.
(författare)
-
A systematic investigation on the accuracy of computer simulations for optical isomers in industrial settings
- 2010
-
Konferensbidrag (refereegranskat)abstract
- Predicting the band profiles of typical chromatographic separations using the approach of the inverse method (IM) [2] requires finding the numerical solution of the Equilibrium-Dispersive (ED) mass balance equation [1]. The accuracy of the determination of the competitive adsorption isotherms is therefore explicitly dependent on the choice of algorithm to solve the ED model. Earlier studies have shown that the well known RFD algorithm [3] has limitations in its accuracy for certain simulated conditions such as column efficiency and adsorption isotherm type [5]. In this study, we thoroughly investigate three different algorithms, the rapid and well known Rouchon Finite Difference (RFD) algorithm [3], the Orthogonal Collocation on Finite Elements (OCFE) method [4] and the Central Difference Method (CDM) algorithm developed by us. Firstly, a systematic investigation is made, comparing the different algorithms under a broad range of different synthetic conditions. Secondly, we apply all three algorithms using the IM on real experimental systems; (I) one high efficiency quaternary separation and (II) one pharmaceutical industry application with a chiral intermediate separation. We have found discrepancies between the conventional (RFD) and the more accurate (OCFE and CDM) algorithms for several synthetic conditions such as low efficiency, increasing number of simulated components and components present at different concentrations. Given high enough efficiency, we experimentally demonstrate good prediction of experimental data of a quaternary separation problem using either algorithm but better prediction of OCFE/CDM for a binary low efficiency separation problem. Our conclusion is to use the RFD algorithm with caution when any of the particular conditions we have investigated is valid. When the highest accuracy is sought, there is no doubt that OCFE or CDM should be the algorithms of choice. However, given the computational speed of RFD, we also recommend it for preliminary parameter fitting. For conditions where we have shown the algorithms to produce practically identical solutions, RFD can be applied with greater certainty. It remains to be thoroughly investigated the effect on the particular shape of the adsorption isotherm on the obtained solution, for example type III having inflection points.
|
|
| 9. |
- Enmark, Martin, et al.
(författare)
-
A thermodynamic and kinetic study of an unusual adsorption behavior-Methyl Mandelate on commercially available Tris-(3,5- dimethylphenyl)carbamoyl Cellulose Chiral Stationary Phase
- 2012
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The adsorption equilibria of racemic methyl mandelate on a tris-(3,5- dimethylphenyl)carbamoyl cellulose chiral stationary phase (CSP) was investigated. The following were observed, the less retained enantiomer shows “Langmuirian†(type I) adsorption behavior, while the adsorption isotherm of the more retained compound contained an inflection point at low concentration. To analyze these differences, adsorption isotherms were determined and further analyzed using Scatchard plots and adsorption energy distribution (AED) calculations. The less retained enantiomer was best described by heterogeneous unimodal adsorption model (Tóth) while the second enantiomer was best described with a heterogeneous adsorption model with adsorbate-adsorbate interactions (bi-Moreau). The adsorption behavior of both enantiomers was also studied at several different temperatures and it was found to be exothermic; in addition, the non-idealadsorbate-adsorbate interaction strength decreases with increasing temperature. Stochastic analysis of the adsorption process could identify a single kinetic site for each enantiomer. The average amount of adsorption/desorption events increases and the sojourn time decreases with increasing temperature. This is an industrial – academic cooperation in the Fundamental Separation Science Group www.separationscience.se
|
|
| 10. |
- Enmark, Martin, et al.
(författare)
-
Adsorption Isotherm Determination for Reliable Phase System Characterization in SFC : Challenges and Pitfalls
- 2012
-
Konferensbidrag (refereegranskat)abstract
- Recently the pharmaceutical industry has started to replace HPLC with SFC because of incentives to lower the environmental impact and as well as increasing performance. Reliable characterization of the adsorption processes in SFC, is therefore of utmost importance. The key thermodynamic phase system information is obtained by rigorous determination of adsorption isotherms over a broad concentration range. If properly processed, this data gives not only correct information about the degree of heterogeneity but also the values of the energy of interactions and monolayer capacities of each individual type of adsorption site in the phase system; ultimately, this can result in identification of the types of interactions (dipole-dipole, van der Waals interactions etc.). In this study, we will present the transfer of LC adsorption characterization methods to SFC conditions using several model compounds with several different methods for adsorption isotherm determination traditionally applied with success in LC, and now modified for SFC. We have limited our investigation to methanol as modifier and used the operational conditions, temperature and backpressure most typically observed in industrial settings; in addition, we have used commercial standard SFC-equipment. The results clearly shows that adsorption isotherm determinations in SFC are considerably more complicated than in LC; we will go through the most important pitfalls and give guidelines for more rigorous determinations of adsorption data in SFC. This is an industrial – academic cooperation in the Fundamental Separation Science Group www.separationscience.se
|
|
| 11. |
- Enmark, Martin, et al.
(författare)
-
Characterization of an unusual adsorption behavior of racemic methyl-mandelate on a tris-(3,5-dimethylphenyl) carbamoyl cellulose chiral stationary phase
- 2011
-
Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673 .- 1873-3778. ; 1218:38, s. 6688-6696
-
Tidskriftsartikel (refereegranskat)abstract
- An interesting adsorption behavior of racemic methyl mandelate on a tris-(3,5-dimethylphenyl)carbamoyl cellulose chiral stationary phase was theoretically and experimentally investigated. The overloaded band of the more retained enantiomer had a peculiar shape indicating a type V adsorption isotherm whereas the overloaded band of the less retained enantiomer had a normal shape indicating a type I adsorption behavior. For a closer characterization of this separation, adsorption isotherms were determined and analyzed using an approach were Scatchard plots and adsorption energy distribution (AED) calculations are combined for a deeper analysis. It was found that the less retained enantiomer was best described by a Tóth adsorption isotherm while the second one was best described with a bi-Moreau adsorption isotherm. The latter model comprises non-ideal adsorbate–adsorbate interactions, providing an explanation to the non-ideal adsorption of the more retained enantiomer. Furthermore, the possibility of using the Moreau model as a local model for adsorption in AED calculations was evaluated using synthetically generated raw adsorption slope data. It was found that the AED accurately could predict the number of adsorption sites for the generated data. The adsorption behavior of both enantiomers was also studied at several different temperatures and found to be exothermic; i.e. the adsorbate–adsorbate interaction strength decreases with increasing temperature. Stochastic analysis of the adsorption process revealed that the average amount of adsorption/desorption events increases and the sojourn time decreases with increasing temperature.
|
|
| 12. |
- Enmark, Martin, et al.
(författare)
-
Characterization of the Adsorption of Racemic Methyl Mandelate on Tris-(3,5-dimethylphenyl)carbamoyl Cellulose Chiral Stationary Phase
- 2011
-
Konferensbidrag (refereegranskat)abstract
- The adsorption equilibria of racemic methyl mandelate on a tris-(3,5-dimethylphenyl)carbamoyl cellulose chiral stationary phase (CSP) was investigated. This separation has previously been performed and analyzed on a methylcellulose tribenzoate coated CSP. In that case, both enantiomers could be described with a bi-Langmuir adsorption isotherm, convex upwards (type I). In our case, two fundamentally different properties were observed. First, the elution order was reversed. Furthermore, only the less retained enantiomer shows type I adsorption behavior, while the adsorption isotherm of the more retained compound contained an inflection point at low concentration. To analyze these differences, adsorption isotherms were determined and further analyzed using Scatchard plots and adsorption energy distribution calculations. The less retained enantiomer was best described by Tóth adsorption isotherm while the second enantiomer was best described with a bi-Moreau adsorption isotherm. The Moreau model is an extension of the Langmuir model including non-ideal adsorbate-adsorbate interactions; here the unusual model provided an explanation to the non-ideal adsorption of the more retained enantiomer. Furthermore, the possibility of using the Moreau model as a local model for adsorption in AED calculations was evaluated by synthetically generated raw adsorption slope data. It was demonstrated that the AED accurately could predict the number of adsorption sites for the generated data. The adsorption behavior of both enantiomers was also studied at several different temperatures and it was found to be exothermic; in addition, the non-idealadsorbate-adsorbate interaction strength decreases with increasing temperature. Stochastic analysis of the adsorption process could identify a single kinetic site for each enantiomer. The average amount of adsorption/desorption events increases and the sojourn time decreases with increasing temperature.
|
|
| 13. |
- Enmark, Martin, et al.
(författare)
-
Computer Assisted Optimization of Pharmaceutical Purification - The Impact of Algorithms and Experimental Approach
- 2010
-
Konferensbidrag (refereegranskat)abstract
- Computer assisted process optimization of chromatographic separations requires the selection of computer algorithms and measurement of relevant parameters. In this study, we will investigate how the choice of algorithms and the number of performed initial experiments affect the estimated optimal separations conditions. We will focus on conditions typically encountered for slurry packing coated 20 µm CSP in large-scale columns used for pharmaceutical intermediate purification.Probably the most essential for parameters in this context are the adsorption isotherm parameters for the components. The rapid "inverse method" is commonly used and this method requires that one numerically solve the mass balance equations describing the chromatographic process. Here we thoroughly investigate how different algorithms that solve the Equilibrium-Dispersive (ED) mass balance equations will affect the estimated adsorption isotherm parameters.Furthermore, we will investigate and compare how different strategies affect the prediction of the optimal separation conditions. First, we will use a more rapid approach that requires a minimum of experiments and uses standard algorithms to estimate optimal conditions. Secondly, we will use a more exact approach that requires more experiments and uses more advanced simulation- and optimization algorithms
|
|
| 14. |
- Enmark, Martin, 1984-, et al.
(författare)
-
Determination of adsorption isotherms in supercritical fluid chromatography
- 2013
-
Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673 .- 1873-3778. ; 1312, s. 124-133
-
Tidskriftsartikel (refereegranskat)abstract
- Abstract In this study we will demonstrate the potential of modern integrated commercial analytical SFC-systems for rapid and reliable acquisition of thermodynamic data. This will be done by transferring the following adsorption isotherm determination methods from liquid chromatography (LC) to supercritical fluid chromatography (SFC): Elution by Characteristic Points (ECP), the Retention Time Method (RTM), the Inverse Method (IM) and the Perturbation Peak (PP) method. In order to transfer these methods to SFC in a reliable, reproducible way we will demonstrate that careful system verification using external sensors of mass flow, temperature and pressure are needed first. The adsorption isotherm data generated by the different methods were analyzed and compared and the adsorption isotherms ability to predict new experimental elution profiles was verified by comparing experiments with simulations. It was found that adsorption isotherm data determined based on elution profiles, i.e., ECP, IM and RTM, were able to accurately predict overloaded experimental elution profiles while the more tedious and time-consuming PP method, based on small injections on concentration plateaus, failed in doing so.
|
|
| 15. |
- Enmark, Martin, et al.
(författare)
-
Enantioseparation of omeprazole effect of different packing particle size on productivity
- 2012
-
Ingår i: Journal of Chromatography A. - Amsterdam : Elsevier. - 0021-9673. ; 1240:1, s. 123-131
-
Tidskriftsartikel (refereegranskat)abstract
- Enantiomeric separation of omeprazole has been extensively studied regarding both product analysis and preparation using several different chiral stationary phases. In this study, the preparative chiral separation of omeprazole is optimized for productivity using three different columns packed with amylose tris (3,5-dimethyl phenyl carbamate) coated macroporous silica (5, 10 and 25 Όm) with a maximum allowed pressure drop ranging from 50 to 400 bar. This pressure range both covers low pressure process systems (50–100 bar) and investigates the potential for allowing higher pressure limits in preparative applications in a future. The process optimization clearly show that the larger 25 Όm packing material show higher productivity at low pressure drops whereas with increasing pressure drops the smaller packing materials have substantially higher productivity. Interestingly, at all pressure drops, the smaller packing material result in lower solvent consumption (L solvent/kg product); the higher the accepted pressure drop, the larger the gain in reduced solvent consumption. The experimental adsorption isotherms were not identical for the different packing material sizes; therefore all calculations were recalculated and reevaluated assuming identical adsorption isotherms (with the 10 Όm isotherm as reference) which confirmed the trends regarding productivity and solvent consumption.
|
|
| 16. |
- Enmark, Martin, 1984-, et al.
(författare)
-
Investigation of plateau methods for adsorption isotherm determination in supercritical fluid chromatography
- 2014
-
Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673 .- 1873-3778. ; 1354, s. 129-138
-
Tidskriftsartikel (refereegranskat)abstract
- The Perturbation Peak (PP) method and Frontal analysis (FA) are considered as the most accurate methods for adsorption isotherms determination in liquid chromatography. In this study we investigate and explain why this is not the case in Supercritical Fluid Chromatography (SFC), where the PP method does not work at all, using a modern analytical system. The main reason was found to be that the solute to be studied must be dissolved in the MeOH reservoir before it is mixed with CO2. Since the solute occupies a certain partial volume in the reservoir, the larger the solute content the larger this fractional volume will be, and the final MeOH fraction in the mobile phase will then be smaller compared to the bulk mobile phase without solute in the modifier. If the retention of small injections on the concentration plateaus, i.e., “analytical-size” perturbation peaks, is sensitive to small variations of MeOH in the eluent, this will seriously decrease the accuracy of the PP method. This effect was verified and compensated for and we also demonstrated that the same problem will occur in frontal analysis, another concentration plateau method.
|
|
| 17. |
- Enmark, Martin, et al.
(författare)
-
On the Reproducibility between Different Modern Supercritcal Fluid Chromatographic Systems
- 2013
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Three different, commercially available, Supercritical Fluid Chromatography (SFC) systems were investigated: Thar Super Pure Discovery Series SFC, Waters UPC2 and Agilent 1260 Infinity SFC. The reason for choosing the two analytical systems from Agilent and Waters is that they represent two of the latest commercial systems available while the semi-preparative instrument was added to widen the study to include instruments also used for preparative purposes. With identical operational conditions set these systems were used to acquire analytical retention data and adsorption isotherms from overloaded injections. The investigation was limited to the use of methanol as modifier and operational conditions, temperature and back pressure most typically observed when utilizing SFC to separate polar compounds. The results clearly show that both analytical retention times and elution profiles are system dependent. Since the overloaded elution profiles are system dependent the adsorption isotherm will also be different. However, this do not mean that the adsorption is different, instead this it is due to the fact that identical instrumental settings, especially pressure and modifier composition settings, does not necessarily mean that the conditions inside the column are identical. This means that it is not possible to transfer an established separation method from one system to another, even if one is using the same column and identical instrument settings. Understanding of SFC-systems will be of fundamental importance for successful transfer of methods between systems, reliable adsorption isotherm determination, and analytical quality work and scaling up from analytical to preparative mode. These issues can probably be solved by measuring mass flow, pressure and temperature along the column, together with a sound understanding of the density variations of the mobile phase. However, the work of finding acceptable applications or guidelines to remove the tedious need for these measurements is currently investigated in our lab. This is a contribution from the Fundamental Separation Science Group www.FSSG.se
|
|
| 18. |
- Enmark, Martin, et al.
(författare)
-
Preparative Separation of Chiral Pharmaceutical Compounds - The Effects of Packing Particle Size, Pressure Limit and Column Geometry on Productivity and Solvent Consumption
- 2011
-
Konferensbidrag (refereegranskat)abstract
- In this study, omeprazole was used as a model compound. Omeprazole and other related sulfoxidebenzimidazolesare used against gastric ulcersand have been extensively studied regarding chromatographic resolution techniques using several different chiral stationary phases.First, AstraZeneca launched Losec, a racemic mixture of RS-omeprazole. Facing loss of patent, the more potent S-enantiomer was developed and marketed as Nexium. Now the patent of Nexium is close expiration why methods for isolation of the pure S-enantiomer will be of importance for the generic pharmaceutical companies.The experimental model separation system represents a system with good selectivity and high solubility of the solute in the eluent. In this investigation the productivity optima for three different particle sizes (5, 10 and 25 µm) at maximum system pressure ranging from 50 to 400 bars are studied. Two different optimizations cases were studied in depth. First,a process optimization with fixed column geometry is studied. The results clearly show that larger packing materials have higher productivity at low pressure drops on the analytical size column.With increasing allowed pressure drops, over 200 bar, the smaller packing materials have substantially higher productivity. The results also show that smaller packing material will always have much lower solvent consumption compared to larger particles.The second process optimization was performed with a fixed column volume, but the column geometry was variable. The results shows that the productivity obtained for the smaller packing particles materials was higher compared to the large for all allowed pressure drops. The productivity obtained for the small particle compared to the large increased by 25-300 % while maintaining 50-300 % less solvent consumption for the purification of the first enantiomer.The addition of TEA seems to be unfavorable for all tested conditions.In conclusion, the optimization of the enantioseparation of omeprazole has been shown to be dependent on column packing particle size as well as column geometry. It has been demonstrated that all parameters need to be simultaneously optimized to reach a global productivity optima.
|
|
| 19. |
- Enmark, Martin, et al.
(författare)
-
Preparative Separation of Omeprazole: Predictions of the Optimal Experimental Conditions by Computer Simulations
- 2011
-
Konferensbidrag (refereegranskat)abstract
- In this study, omeprazole was used as a model compound. Omeprazole and other related sulfoxide benzimidazoles are used against gastric ulcers and have been extensively studied regarding chromatographic resolution techniques using several different chiral stationary phases.First, AstraZeneca launched Losec, a racemic mixture of RS-omeprazole. Facing loss of patent, the more potent S-enantiomer was developed and marketed as Nexium. Now the patent of Nexium is close expiration why methods for isolation of the pure S-enantiomer will be of importance for the generic pharmaceutical companies.The experimental model separation system represents a system with good selectivity and high solubility of the solute in the eluent. In this investigation the productivity optima for three different particle sizes (5, 10 and 25 µm) at maximum system pressure ranging from 50 to 400 bars are studied. Two different optimizations cases were studied in depth. First,a process optimization with fixed column geometry is studied. The results clearly show that larger packing materials have higher productivity at low pressure drops on the analytical size column.With increasing allowed pressure drops, over 200 bar, the smaller packing materials have substantially higher productivity.The results also show that smaller packing material will always have much lower solvent consumption compared to larger particles.The second process optimization was performed with a fixed column volume, but the column geometry was variable. The results shows that the productivity obtained for the smaller packing particles materials was higher compared to the large for all allowed pressure drops. The productivity obtained for the small particle compared to the large increased by 25-300 % while maintaining 50-300 % less solvent consumption for the purification of the first enantiomer.The addition of TEA seems to be unfavorable for all tested conditions.In conclusion, the optimization of the enantioseparation of omeprazole has been shown to be dependent on column packing particle size as well as column geometry. It has been demonstrated that all parameters need to be simultaneously optimized to reach a global productivity optima.
|
|
| 20. |
|
|
| 21. |
- Enmark, Martin, et al.
(författare)
-
Using Modern SFC Systems for Adsorption Characterization
- 2013
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Recently the pharmaceutical industry has started to replace preparative HPLC with preparative SFC to lower the environmental impact and to increase performance. Reliable characterization of the adsorption processes in SFC is therefore of utmost importance. The key thermodynamic phase system information is obtained by rigorous determination of adsorption isotherm data over a broad concentration range. If properly processed, this data gives not only correct information about the degree of heterogeneity but also the energy of interactions and mono layer capacities of each individual type of adsorption site in the phase system. Ultimately, this can result in identification of the types of interactions, i.e., dipole-dipole, van der Waals interactions etc. In this study we will present transfer of selected adsorption characterization methods, traditionally applied with success in LC, to SFC. We have here transferred all available knowledge from LC – from model selection to validation. We will also, using recent findings, explain the effects of pressure and temperature variations as well as how to accurately measure the volumetric flow rate on a modern analytical SFC system. We will demonstrate how the latest SFC instruments, with some critical modifications; have the potential for rapid and reliable acquisition of thermodynamic data using the ECP method. Finally we will elaborate on how the adsorption depends on density, temperature and modifier content in the mobile phase. This is a contribution from the Fundamental Separation Science Group www.FSSG.se
|
|
| 22. |
- Erhardt, Sophie, et al.
(författare)
-
Connecting Inflammation with Glutamate Agonism in Suicidality
- 2013
-
Ingår i: Neuropsychopharmacology. - : Nature Publishing Group: Open Access Hybrid Model Option A. - 0893-133X .- 1740-634X. ; 38:5, s. 743-752
-
Tidskriftsartikel (refereegranskat)abstract
- The NMDA-receptor antagonist ketamine has proven efficient in reducing symptoms of suicidality, although the mechanisms explaining this effect have not been detailed in psychiatric patients. Recent evidence points towards a low-grade inflammation in brains of suicide victims. Inflammation leads to production of quinolinic acid (QUIN) and kynurenic acid (KYNA), an agonist and antagonist of the glutamatergic N-methyl-D-aspartate (NMDA) receptor, respectively. We here measured QUIN and KYNA in the cerebrospinal fluid (CSF) of 64 medication-free suicide attempters and 36 controls, using gas chromatography mass spectrometry and high-performance liquid chromatography. We assessed the patients clinically using the Suicide Intent Scale and the Montgomery Asberg Depression Rating Scale (MADRS). We found that QUIN, but not KYNA, was significantly elevated in the CSF of suicide attempters (Pandlt;0.001). As predicted, the increase in QUIN was associated with higher levels of CSF interleukin-6. Moreover, QUIN levels correlated with the total scores on Suicide Intent Scale. There was a significant decrease of QUIN in patients who came for follow-up lumbar punctures within 6 months after the suicide attempt. In summary, we here present clinical evidence of increased QUIN in the CSF of suicide attempters. An increased QUIN/KYNA quotient speaks in favor of an overall NMDA-receptor stimulation. The correlation between QUIN and the Suicide Intent Scale indicates that changes in glutamatergic neurotransmission could be specifically linked to suicidality. Our findings have important implications for the detection and specific treatment of suicidal patients, and might explain the observed remedial effects of ketamine. Neuropsychopharmacology (2013) 38, 743-752; doi:10.1038/npp.2012.248; published online 9 January 2013
|
|
| 23. |
- Fornstedt, Torgny, et al.
(författare)
-
New Procedure for Predictions of Overloaded Profiles in Gradient Elution
- 2013
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- To simulate the separation process in liquid chromatography, the competitive adsorption isotherms need to be known. In gradient elution, the adsorption isotherms are determined with isocratic experiments on different mobile-phase plateaus, levels covering the range used in the gradient program. This can lead to extreme retention times for some mobile-phase compositions and therefore it might even be impossible to determine all necessary adsorption data using the traditional isocratic approach. In this talk, we will present a method where single and competitive nonlinear adsorption isotherms are determined directly from overloaded elution profiles in gradient elution. The numerical coefficients in the adsorption isotherms are determined by the inverse method that minimizes the difference between calculated and experimental elution profiles. This is a new method where the need for tedious/impossible isocratic experiments is eliminated. The method is systematically verified using both synthetic and experimental data. Finally the new method is used to successfully predict elution profiles for a two-component mixture in gradient elution. The new method open up the opportunity to study the adsorption of substances whose retention factor vary strongly with the mobile-phase composition, like peptides and proteins, where the classic methods will fail. We also intend to transfer the metholology for SFC in near future; but there are some problems to be solved first (see our SFC posters). This is a contribution from the Fundamental Separation Science Group www.FSSG.se
|
|
| 24. |
|
|
| 25. |
|
|
| 26. |
- Hillerström, Anna, et al.
(författare)
-
Solvent strategies for loading and release in mesoporous silica
- 2014
-
Ingår i: Colloid and Interface Science Communications. - Amsterdam : Elsevier BV. - 2215-0382. ; 3, s. 5-8
-
Tidskriftsartikel (refereegranskat)abstract
- A model molecule, ibuprofen, was loaded in the pores of mesoporous silica by adsorption from nonpolar solvents (liquid carbon dioxide and cyclohexane) and from a polar solvent (methanol). It was sufficient with a very low concentration of ibuprofen in the nonpolar solvents to achieve maximum loading of ibuprofen in the mesoporous particles. When using liquid carbon dioxide, the pores of the mesoporous silica particles were filled completely with ibuprofen at a lower ibuprofen concentration than similar experiments performed with cyclohexane. When methanol was used, the maximum amount of loaded ibuprofen was never achieved. Furthermore, x-ray scattering showed that all ibuprofen loaded into the mesoporous particles were in an amorphous state. Ibuprofen was released from the mesoporous particles to water within a couple of minutes, regardless of solvent used for loading. It was found that the release of ibuprofen from mesoporous silica was much faster than that of crystalline ibuprofen.
|
|
| 27. |
- Janelidze, Shorena, et al.
(författare)
-
Altered chemokine levels in the cerebrospinal fluid and plasma of suicide attempters
- 2013
-
Ingår i: Psychoneuroendocrinology. - : Elsevier. - 0306-4530 .- 1873-3360. ; 38:6, s. 853-862
-
Tidskriftsartikel (refereegranskat)abstract
- Chemokines constitute a class of small inflammatory proteins that control the chemotaxis of leukocytes. They are also present in the central nervous system (CNS) and contribute to diverse physiological functions, such as the regulation of cell migration, axonal growth and neuronal survival. It is to date not known whether chemokines in the CNS are affected in psychiatric disorders. In this study, chemokine levels were measured in the cerebrospinal fluid (CSF) of 137 psychiatric patients in conjunction to a suicide attempt, and 43 healthy controls. A subgroup of patients (n = 42) was followed up with blood samples 12 years after the initial CSF collection, when they did not show suicidal behavior. The follow-up chemokine levels were compared to those of psychiatric patients (n = 17) who had never attempted suicide. Ultrasensitive chemokine multiplex immunoassay was used to quantify eotaxin-1 (CCL11), interferon gamma-induced protein-10 (IP-10, CXCL10), macrophage inflammatory protein-1 beta (MIP-1 beta, CCL4), monocyte chemotactic protein-1 (MCP-1, CCL2), MCP-4 (CCL13) and thymus and activation regulated chemokine (TARC, CCL17). Patients were diagnosed using DSM-III-R/DSM-IV, and assessed using the Comprehensive Psychopathological Rating Scale (CPRS), including subscales, and the Suicidal Intent Scale (SIS). CSF eotaxin-1, MIP-1 beta, MCP-1, MCP-4 and TARC were significantly lower in suicide attempters than in healthy controls. Low chemokine levels were specifically associated with psychotic symptoms and pain. In the samples collected at follow-up, TARC was significantly lower in suicide attempters compared to psychiatric patients who had never attempted suicide. We also found a positive correlation between blood TARC and brain-derived neurotrophic factor (BDNF) levels. Our study thus provides evidence of reduced chemokine levels in suicide attempters, both in the acute suicidal setting, and at long-term, compared to non-attempters. These results warrant future studies on the detailed neurobiological functions of chemokines in psychiatric patients. (C) 2012 Elsevier Ltd. All rights reserved.
|
|
| 28. |
- Johansson, Johas, et al.
(författare)
-
Tekniska Infrastruktures sårbarhet
- 2010
-
Ingår i: FRIVA - risk, sårbarhet och förmåga. - 9789163376917 ; , s. 111-128
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
|
|
| 29. |
|
|
| 30. |
- Karlsson, Martin, et al.
(författare)
-
Using operational modal analysis to determine rotordynamic modes
- 2010
-
Ingår i: 13th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery 2010 (ISROMAC-13). - Red Hook, NY : Curran Associates, Inc.. - 9781617388484 ; , s. 527-530
-
Konferensbidrag (refereegranskat)abstract
- Operational Modal Analysis (OMA) has lately been a more and more common tool in structural dynamics. The benefits compared to Experimental Modal Analysis (EMA) are that one does not need any artificial excitation and that the structure does not have to be at rest, which is a requirement of EMA. So far, OMA has won terrain for modal analysis of large structures such as buildings and bridges, and for vehicles such as helicopters and ships. For rotating equipment, OMA has not yet been widely used or evaluated. Rotordynamic modes depend on the operating condition of the rotating equipment (e.g. speed). Hence the fundamental requirement of EMA that the testing object should be at rest is not fulfilled. Mapping of critical speeds during start-up and coursing down gives some important operating information, but it will not give all modal information needed to validate a theoretical model or to verify the requirements of damping. The aim of this paper is to evaluate OMA for rotordynamical modal analysis. A numerical model of rotor is used as test object. The response is analyzed with various SSI methods. The results are presented in a Campbell diagram, showing the frequency dependent rotor modes as well as the structural modes. Values for the damping are presented in a root locus plot. These results agree well when comparing the results with a direct naturalvalue solver for the numerical model. It is concluded that OMA can be applied to rotordynamical applications. However, identifying corresponding modes at different speeds can be difficult at field measurements; hence the authors suggest further research and development of Operational Modal Analysis in this specific area.
|
|
| 31. |
- Kegel, Magdalena E., et al.
(författare)
-
Imbalanced Kynurenine Pathway in Schizophrenia
- 2014
-
Ingår i: International Journal of Tryptophan Research. - : Libertas Academica. - 1178-6469. ; 7, s. 15-22
-
Tidskriftsartikel (refereegranskat)abstract
- Several studies suggest a role for kynurenic acid (KYNA) in the pathophysiology of schizophrenia. It has been proposed that increased brain KYNA levels in schizophrenia result from a pathological shift in the kynurenine pathway toward enhanced KYNA formation, away from the other branch of the pathway leading to quinolinic acid (QUIN). Here we investigate the levels of QUIN in cerebrospinal fluid (CSF) of patients with schizophrenia and healthy controls, and relate those to CSF levels of KYNA and other kynurenine metabolites from the same individuals. CSF QUIN levels from stable outpatients treated with olanzapine (n = 22) and those of controls (n = 26) were analyzed using liquid chromatography-mass spectrometry. No difference in CSF QUIN levels between patients and controls was observed (20.6 ± 1.5 nM vs. 18.2 ± 1.1 nM, P = 0.36). CSF QUIN was positively correlated to CSF kynurenine and CSF KYNA in patients but not in controls. The CSF QUIN/KYNA ratio was lower in patients than in controls (P = 0.027). In summary, the present study offers support for an over-activated and imbalanced kynurenine pathway, favoring the production of KYNA over QUIN in patients with schizophrenia.
|
|
| 32. |
- Larsson, Sylvia, et al.
(författare)
-
Effects of moisture content, torrefaction temperature, and die temperature in pilot scale pelletizing of torrefied Norway spruce
- 2013
-
Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 102, s. 827-832
-
Tidskriftsartikel (refereegranskat)abstract
- Pilot scale pelletizing of torrefied Norway spruce was performed in a factorial design with controlled factors at two levels: material moisture content (11% and 15%) and torrefaction temperature (270 and 300 °C), and die temperature as an uncontrolled factor (60–105 °C). Compared to commercial wood pellets, produced pellets had comparable bulk densities (630–710 kg/m3) but lower pellet durability (80–90%). Energy consumption for pelletizing of torrefied materials was approximately 100% higher than for softwood pelletizing, despite using a much shorter die channel length (35 vs. 55 mm:s), and the amounts of fines were high (10–30%). Die temperature showed a strong positive correlation with pellet production rate. Material moisture content had little influence on pellet quality and production rate, but addition of water created handling problems due to bad flow behavior.
|
|
| 33. |
- Linderholm, Klas R, et al.
(författare)
-
Increased Levels of Kynurenine and Kynurenic Acid in the CSF of Patients With Schizophrenia
- 2012
-
Ingår i: Schizophrenia Bulletin. - : Oxford University Press. - 0586-7614 .- 1745-1701. ; 38:3, s. 426-432
-
Tidskriftsartikel (refereegranskat)abstract
- Background: The kynurenic acid (KYNA) hypothesis for schizophrenia is partly based on studies showing increased brain levels of KYNA in patients. KYNA is an endogenous metabolite of tryptophan (TRP) produced in astrocytes and antagonizes N-methyl-D-aspartate and alpha7* nicotinic receptors. Methods: The formation of KYNA is determined by the availability of substrate, and hence, we analyzed KYNA and its precursors, kynurenine (KYN) and TRP, in the cerebrospinal fluid (CSF) of patients with schizophrenia. CSF from male patients with schizophrenia on olanzapine treatment (n = 16) was compared with healthy male volunteers (n = 29). Results: KYN and KYNA concentrations were higher in patients with schizophrenia (60.7 +/- 4.37nM and 2.03 +/- 0.23nM, respectively) compared with healthy volunteers (28.6 +/- 1.44nM and 1.36 +/- 0.08nM, respectively), whereas TRP did not differ between the groups. In all subjects, KYN positively correlated to KYNA. Conclusion: Our results demonstrate increased levels of CSF KYN and KYNA in patients with schizophrenia and further support the hypothesis that KYNA is involved in the pathophysiology of schizophrenia.
|
|
| 34. |
- Nilsson, Magnus, et al.
(författare)
-
Discovery of 4 '-azido-2 '-deoxy-2 '-C-methyl cytidine and prodrugs thereof : A potent inhibitor of Hepatitis C virus replication
- 2012
-
Ingår i: Bioorganic & Medicinal Chemistry Letters. - : Elsevier BV. - 0960-894X .- 1464-3405. ; 22:9, s. 3265-3268
-
Tidskriftsartikel (refereegranskat)abstract
- 4'-Azido-2'-deoxy-2'-methylcytidine (14) is a potent nucleoside inhibitor of the HCV NS5B RNA-dependent RNA polymerase, displaying an EC50 value of 1.2 mu M and showing moderate in vivo bioavailability in rat (F = 14%). Here we describe the synthesis and biological evaluation of 4'-azido-2'-deoxy-2'-methylcytidine and prodrug derivatives thereof. (C) 2012 Elsevier Ltd. All rights reserved.
|
|
| 35. |
- Olsson, Sara K., et al.
(författare)
-
Elevated levels of kynurenic acid in the cerebrospinal fluid of patients with bipolar disorder
- 2010
-
Ingår i: Journal of Psychiatry & Neuroscience. - : CMA Joule Inc.. - 1180-4882 .- 1488-2434. ; 35:3, s. 195-199
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Patients with schizophrenia show elevated brain levels of the neuroactive tryptophan metabolite kynurenic acid (KYNA) This astrocyte] derived mediator acts as a neuroprotectant and modulates sensory gating and cognitive functiona We measured the levels of KYNA in the cerebrospinal fluid T vSyU of patients with bipolar disorder and healthy volunteers to investigate the putative involvement of KYNA in bipolar disorder. Methods: We obtained CSF by lumbar puncture from 23 healthy men and 31 euthymic men with bipolar disorder. We analyzed the samples using high] performance liquid chromatography. Results: Patients with bipolar disorder had increased levels of KYNA in their CSF compared with healthy volunteers (1.71 nM, standard error of the mean [SEM] cad, va dad, nM, SEM cacln p = 0.002. The levels of KYNA were positively correlated with age among bipolar patients but not healthy volunteersa Limitations: The influence of ongoing drug treatment among patients cannot be ruled outa We conducted our study during the euthymic phase of the diseasea Conclusion: Brain KYNA levels are increased in euthymic men with bipolar disorder. In addition, KYNA levels increased with age in these patientsa These findings indicate shared mechanisms between bipolar disorder and schizophrenia. Elevated levels of brain KYNA may provide further insight to the pathophysiology and progression of bipolar disorder.
|
|
| 36. |
- Samuelsson, Jörgen, et al.
(författare)
-
Characterization of adsorption in SFC : An evaluation of methods used in LC
- 2012
-
Konferensbidrag (refereegranskat)abstract
- Recently the pharmaceutical industry has started to replace HPLC with SFC because of incentives to lower the environmental impact and as well as increasing performance. Reliable characterization of the adsorption processes in SFC, is therefore of utmost importance. The key thermodynamic phase system information is obtained by rigorous determination of adsorption isotherms over a broad concentration range. If properly processed, this data gives not only correct information about the degree of heterogeneity but also the values of the energy of interactions and monolayer capacities of each individual type of adsorption site in the phase system; ultimately, this can result in identification of the types of interactions (dipole-dipole, van der Waals interactions etc.). In this study, we will present the transfer of LC adsorption characterization methods to SFC conditions using several model compounds with several different methods for adsorption isotherm determination traditionally applied with success in LC, and now modified for SFC. We have limited our investigation to methanol as modifier and used the operational conditions, temperature and backpressure most typically observed in industrial settings; in addition, we have used commercial standard SFC-equipment. The results clearly shows that adsorption isotherm determinations in SFC are considerably more complicated than in LC; we will go through the most important pitfalls and give guidelines for more rigorous determinations of adsorption data in SFC. This is an industrial – academic cooperation in the Fundamental Separation Science Group www.separationscience.se
|
|
| 37. |
- Samuelsson, Jörgen, et al.
(författare)
-
Highlighting Important Parameters Often Neglected in Numerical Optimization of Preparative Chromatography
- 2012
-
Ingår i: Chemical Engineering & Technology. - : Wiley. - 0930-7516 .- 1521-4125. ; 35:1, s. 149-156
-
Tidskriftsartikel (refereegranskat)abstract
- When a chromatographic separation process is numerically optimized, a number of input parameters to the column model need to be accurately determined, and the accuracy will affect the reliability of the predicted optimal operational conditions. Furthermore, the numerical accuracy of the solution to the column model will have similar impact. The input parameters holdup volume, injection profiles, and the selection of an algorithm for solving the column model were investigated. Errors in parameters or a numerical error in the solution of the column model were found to lead to a prediction of a product fraction where the set purity and/or yield requirements are not met.
|
|
| 38. |
- Samuelsson, Jörgen, et al.
(författare)
-
Modeling Competitive Adsorption Isotherms in Gradient Elution Nonlinear Reversed Phase Liquid Chromatography.
- 2012
-
Konferensbidrag (refereegranskat)abstract
- Several important studies – based on firm theory ground - have been made on the different parameters of importance in chromatographic process optimizations during the recent years. In this presentation we take an holistic view by investigating i) the relative importance of the operational parameters and column properties and ii) how these effect the optimal column design. For optimization we used an advanced global response surface method combined with local gradient methods. As a model system we used the practical problem of purification of one or both optical isomers of a racemate. In the first part, we investigated the relative importance of stationary phase characteristics such as: (i) the retention factor, (ii) the selectivity, (iii) the saturation capacity (iv), the efficiency and (v) the maximum allowed operational pressure. In the second part we investigated how the optimal column design for a preparative separation problem is affected by column properties, such as particle size, and optimization constraints, such as required yield. The investigation showed – in contrast to what is generally believed – that the saturation capacity of the stationary phase is of minor importance, instead the maximum allowed operational pressure is one of the most important parameter. Moreover, smaller size packing materials always shows much lower solvent consumption. This is a great environmental and economical advantage of using smaller packing materials. Rules of thumbs, derived from the holistic optimizations, will be given for industrial preparative settings in the batch mode.
|
|
| 39. |
- Samuelsson, Martin, et al.
(författare)
-
Glutathione in the blood and cerebrospinal fluid: A study in healthy male volunteers
- 2011
-
Ingår i: Neuropeptides. - : Elsevier. - 0143-4179 .- 1532-2785. ; 45:4, s. 287-292
-
Tidskriftsartikel (refereegranskat)abstract
- Glutathione (GSH) is an important regulator of intracellular redox homeostasis. In the brain, glutathione is considered a major antioxidant, which is also found at high concentrations in the extracellular environment. Altered GSH balance in plasma, blood and cerebrospinal fluid (CSF) has been observed in several disorders suggesting that an impaired antioxidant function is part of the pathophysiology. The aim of the present study was to investigate a possible relationship between glutathione in plasma and CSF. Blood samples were collected from 26 healthy male volunteers at 8 a.m., noon, 4 p.m. and 8 p.m. At 8 a.m. the following morning, blood was drawn and three 6-ml fractions of CSF were collected by lumbar puncture. In CSF, a disrupted gradient was found showing the highest glutathione concentration in the second compared to the first and third fraction (P andlt; 0.002). Moreover, correlation and regression analyses between glutathione in plasma and CSF revealed an association between the third fraction CSF and plasma glutathione 8 p.m. the day before lumbar puncture. Thus, if carefully standardised due to the disrupted gradient in CSF, it might be possible to estimate glutathione levels in CSF by analysing plasma in healthy males.
|
|
| 40. |
- Samuelsson, Martin, 1965-
(författare)
-
Taurine and Glutathione in cerebrospinal fluid and plasma from patients with psychiatric disorders and healthy controls
- 2012
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A growing body of results indicate that immunological alterations and oxidative stress are of importance in various mental disorders. The inflammatory changes are possible to detect both in plasma and cerebrospinal fluid (CSF), and different psychiatric disorder exhibit similar changes indicating a common underlying mechanism. The antioxidants are of importance to regulate the redox balance and control the inflammatory processes but the causal relationship between psychiatric disorders and increased oxidative stress is however not fully clarified. Two important antioxidants; taurine and glutathione (GSH), have been suggested to have central nervous system (CNS)-protective properties. They have been found to fluctuate in several mental disorders including schizophrenia and depression but the clinical relevance need further studies.The general aim of this thesis was to increase the understanding of taurine and the GSH in depression and schizophrenia, two major mental disorders, in comparison to healthy controls.Correlations between glutathione and taurine levels in blood and CSF were analyzed in healthy male volunteers and we identified a complex pattern of associations showing that the CSF concentration was influenced by body mass index (BMI), age, intraspinal pressure, plasma concentrations the previous day and possible genetic factors. Electroconvulsive therapy (ECT) is used in the treatment of severely depressed patients. In blood collected before the first and after the third ECT, we found a significant decrease in plasma taurine in patients responding to the treatment, while total glutathione was unaltered. In a group of olanzapine treated patients with schizophrenia or schizoaffective disorders, we analysed taurine and glutathione in plasma and CSF and compared with healthy male and female volunteers. We observed increased plasma taurine levels in patients compared with controls, but no difference in CSF taurine and no alteration in glutathione.This thesis indicates that taurine might play a role in mental disorders such as depression and schizophrenia. Increased knowledge about the complex regulation of taurine and glutathione might provide new insights into the impact of redox balance in the pathophysiology of psychiatric disorder and contribute to a future personalization of the treatment.
|
|
| 41. |
- Samuelsson, Martin, et al.
(författare)
-
Taurine and glutathione in plasma and cerebrospinal fluid in olanzapine treated patients with schizophrenia
- 2013
-
Ingår i: Psychiatry Research. - : Elsevier. - 0165-1781 .- 1872-7123. ; 210:3, s. 819-824
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives: Oxidative stress has been implicated in the pathophysiology of schizophrenia. Taurine and glutathione (GSH) have antioxidant and central nervous system protective properties and are proposed to be involved in the pathology of schizophrenia. The aim of this study was to compare the blood and cerebrospinal fluid (CSF) levels of taurine and GSH in patients with schizophrenia medicated with oral olanzapine compared with controls.Methods: In total, 37 patients with schizophrenia being medicated with olanzapine and 45 healthy volunteers were recruited. Taurine and GSH levels were analysed in plasma and CSF and correlated to symptoms and level of function.Results: Plasma taurine levels were elevated in patients compared with controls (p=0.000003). No differences were found between patients and controls regarding taurine in CSF or GSH concentrations in plasma and CSF.Conclusion: The significantly higher levels of plasma but not CSF taurine in patients with schizophrenia treated with olanzapine compared with controls may implicate the involvement of taurine in the pathophysiology of the disease. The absence of GSH differences in plasma and CSF between patients and controls is interesting in the perspective of earlier research proposing a dysregulation of GSH metabolism as a vulnerability factor for the development of schizophrenia.
|
|
| 42. |
- Samuelsson, Martin, et al.
(författare)
-
Taurine and glutathione levels in plasma before and after ECT treatment
- 2012
-
Ingår i: Psychiatry Research. - : Elsevier Science B.V., Amsterdam.. - 0165-1781 .- 1872-7123. ; 198:1, s. 53-57
-
Tidskriftsartikel (refereegranskat)abstract
- Taurine has been shown to be elevated in plasma and lymphocytes of depressed patients, but the level normalises after successful drug therapy. During depression, levels of glutathione (GSH) are decreased in the plasma and blood. This study was performed to examine taurine and GSH levels in depressed patients before and after electroconvulsive therapy (ECT). Fasting blood samples were collected from 23 patients before the first and after the third ECT treatment. The severity of depression was estimated with the Montgomery–Åsberg Depression Rating Scale (MADRS). We analysed GSH in blood and the levels of taurine and total GSH in plasma. After three ECTs, a significant decrease in MADRS scores was found for the entire group. Simultaneously, the decrease in the plasma taurine levels was significant for the seven responders but not for the sixteen non-responders. We observed no differences in blood or plasma GSH levels after three ECT treatments when compared to values before the therapy. Plasma taurine levels decrease significantly after three ECT treatments in patients who respond to treatment. GSH levels were not affected by ECT treatment. The results indicate that taurine may play a role in the pathophysiology of depression.
|
|
| 43. |
|
|
| 44. |
- Samuelsson, Ulli
(författare)
-
Digital (o)jämlikhet? IKT-användning i skolan och elevers tekniska kapital
- 2014
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Avhandlingen handlar om digital (o)jämlikhet. Begreppet (o)jämlikhet utgår från en sammanskrivning av jämlikhet och ojämlikhet men uttalas som det sistnämnda. Problematiken kring digital (o)jämlikhet belyses i avhandlingen i form av fyra olika delstudier samt en kappa.Avhandlingens övergripande syfte är att öka kunskapen om digital (o)jämlikhet genom att empiriskt kartlägga och teoretiskt tolka användning av informations- och kommunikationsteknik (IKT) bland barn och unga vuxna. Ett speciellt fokus läggs vid skolans roll i sammanhanget då den svenska skolan har i sitt uppdrag att ge alla elever en likvärdig utbildning. Skolan ska även kompensera för elevers olika förutsättningar. Genom en enkätstudie och en intervjustudie analyseras grundskole- och gymnasielevers användning av och tillgång till IKT i skolan och i hemmen. Elevernas digitala kompetens i allmänhet och deras kompetens i informationssökning i synnerhet, analyseras också för att skapa en bild av den digitala (o)jämlikheten. I dessa analyser studeras även skolans bidrag till elevers digitala kompetens och digitala jämlikhet. Resultaten av dessa analyser presenteras i två delstudier.För att få en djupare förståelse för fenomenet digital (o)jämlikhet ur ett internationellt perspektiv utgör en av delstudierna en systematisk forskningsöversikt. Ytterligare ett sätt att fördjupa kunskapen om digital (o)jämlikhet i avhandlingen är att studera fenomenet utifrån en utbildningssociologisk teori vilket genomförs i den sista delstudien. Inom ramen för det övergripande syftet prövas, och granskas kritiskt, därför Selwyns begrepp tekniskt kapital. Tekniskt kapital har sin grund i Bourdieus kapitalbegrepp och syftar därmed på tillgång till och användning av IKT som tillskrivs ett värde.Resultaten visar att det finns en digital ojämlikhet bland de unga som ingår i studien, trots den till synes höga tillgången till IKT. Avhandlingen visar även att skolan inte klarar sitt uppdrag då eleverna inte får en likvärdig utbildning samt att skolans uppdrag avseende elevers digitala kompetens är oklart. Vidare visar resultatet att begreppet teknisk kapital ger möjlighet till en djupare förståelse av digital (o)jämlikhet. Samtidigt ges förslag på hur begreppet tekniskt kapital kan förfinas ytterligare.
|
|
| 45. |
|
|
| 46. |
- Söderlund, Johan, et al.
(författare)
-
Elevation of cerebrospinal fluid interleukin-1ß in bipolar disorder.
- 2010
-
Ingår i: Journal of psychiatry & neuroscience : JPN. - : CMA Joule Inc.. - 1488-2434 .- 1180-4882. ; 35:6
-
Tidskriftsartikel (refereegranskat)abstract
- Background: In recent years, a role for the immune system in the pathogenesis of psychiatric diseases has gained increased attention. Although bipolar disorder appears to be associated with altered serum cytokine levels, a putative immunological contribution to its pathophysiology remains to be established. Hitherto, no direct analyses of cerebrospinal fluid (CSF) cytokines in patients with bipolar disorder have been performed. Methods: We analyzed CSF cytokine concentrations in euthymic patients with diagnosed bipolar dis order type I (n = 15) or type II (n = 15) and healthy volunteers (n = 30) using an immunoassay-based protein array multiplex system. Results: The mean interleukin (IL)-1ß level (4.2 pg/mL, standard error of the mean [SEM] 0.5) was higher and the IL-6 level (1.5 pg/mL, SEM 0.2) was lower in euthymic bipolar patients than in healthy volunteers (0.8 pg/mL, SEM 0.04, and 2.6 pg/mL, SEM 0.2, respect ively). Patients with 1 or more manic/hypomanic episodes during the last year showed significantly higher levels of IL-1ß (6.2 pg/mL, SEM 0.8; n = 9) than patients without a recent manic/hypomanic episode (3.1 pg/mL, SEM 1.0; n = 10). Limitations: All patients were in an euthymic state at the time of sampling. Owing to the large variety of drugs prescribed to patients in the present study, influence of medication on the cytokine profile cannot be ruled out. Conclusion: Our findings show an altered brain cytokine profile associated with the manifestation of recent manic/hypomanic episodes in patients with bipolar disorder. Although the causality remains to be established, these findings may suggest a pathophysiological role for IL-1ß in bipolar disorder.
|
|
| 47. |
- Vanfretti, Luigi, et al.
(författare)
-
Estimation of Eastern Denmark’s electromechanical modes from ambient phasor measurement data
- 2010
-
Ingår i: IEEE POWER AND ENERGY SOCIETY GENERAL MEETING 2010. - : IEEE. - 9781424483570 ; , s. 1-8
-
Konferensbidrag (refereegranskat)abstract
- In this paper we report on the preliminary results of a collaborative investigation effort between researchers in North America and Europe aiming to baseline the electromechanical modes and mode shapes of the Nordic system from synchronized phasor measurement data. We provide an overview on the Danish power grid and its interconnections, and describe the features of an experimental phasor measurement unit designed by DTU which is used to provide the measurements used in this investigation. Parametric and non-parametric block processing techniques are applied to 48 hours of ambient data recorded at the Radsted and Hoveg #x00E5;rd substations in Eastern Denmark. The estimated modes are in agreement with those shown in eigenanalysis studies, and other measurement-based investigations. More importantly, the emergence of a new 0.8 Hz mode in Sj #x00E6;lland is reported.
|
|
| 48. |
- Widerström, Micael, et al.
(författare)
-
Large outbreak of cryptosporidium hominis infection transmitted through the public water supply, Sweden
- 2014
-
Ingår i: Emerging Infectious Diseases. - : Centers for Disease Control and Prevention (CDC). - 1080-6040 .- 1080-6059. ; 20:4, s. 581-589
-
Tidskriftsartikel (refereegranskat)abstract
- In November 2010, approximate to 27,000 (approximate to 45%) inhabitants of Östersund, Sweden, were affected by a waterborne outbreak of cryptosporidiosis. The outbreak was characterized by a rapid onset and high attack rate, especially among young and middle-aged persons. Young age, number of infected family members, amount of water consumed daily, and gluten intolerance were identified as risk factors for acquiring cryptosporidiosis. Also, chronic intestinal disease and young age were significantly associated with prolonged diarrhea. Identification of Ctyptosporidium hominis subtype lbA10G2 in human and environmental samples and consistently low numbers of oocysts in drinking water confirmed insufficient reduction of parasites by the municipal water treatment plant. The current outbreak shows that use of inadequate microbial barriers at water treatment plants can have serious consequences for public health. This risk can be minimized by optimizing control of raw water quality and employing multiple barriers that remove or inactivate all groups of pathogens.
|
|
| 49. |
- Åsberg, Dennis, et al.
(författare)
-
An Experimental and Theoretical investigation on Mobile PhaseEffects on Competitive Adsorption Isotherms in Preparative LC
- 2012
-
Konferensbidrag (refereegranskat)abstract
- This poster serves as background information to the corresponding lecture. Mobile phase gradients have been used in LC since the 1950s and are still an important programming technique in both analytical and preparative LC. Improving the resolution, and thereby making the separation of complex samples possible, and reducing the separation time, which increases the productivity, are the two main advantages of gradient elution. The modelling of band profiles and the optimization of preparative separations has largely been studied under isocratic conditions. The shape of the gradient and the behaviour of the solutes are often determined experimentally with scarce knowledge about the underlying physicochemical equations. This "trial and error" approach results in time consuming and, possibly, expensive experiments. The goal of this work is to investigate the dependence of the adsorption behaviour on the mobile phase composition in reversed phase LC. By knowing the adsorption isotherm as a function of the concentrations of both the solute and the strong organic modifier, the band profiles are modelled under gradient elution conditions.Our aim is to make it possible to use modelling tools so one can optimize a separation and especially the gradient shape. Recent studies have shown that a significant improvement in productivity can be achieved if the gradient shapes are designed carefully [1,2].In this study we discuss how to obtain the adsorption isotherm data experimentally for two substances using the perturbation peak method. The substances which are investigated are cyclohexanone and cycloheptanone on a Kromasil C18-column with methanol-water as the mobile phase. The fitting of the nonlinear experimental data to appropriate theoretical isotherm models will also be discussed.For practical reasons, we will also be looking at how different key parameters, e.g. the column hold-up time, the column efficiency, the retention factor and the equilibrium constant, change with the mobile phase composition.With the experimentally determined adsorption isotherm as a basis, we will simulate overloaded band profiles under gradient elution conditions and compare the simulated results with experimentally obtained band profiles.A contribution from the Fundamental Separation Science Group www.separationscience.se
|
|
| 50. |
- Åsberg, Dennis, 1988-, et al.
(författare)
-
Evaluation of co-solvent fraction, pressure and temperature effects in analytical and preparative supercritical fluid chromatography
- 2014
-
Ingår i: Journal of Chromatography A. - : Elsevier. - 0021-9673 .- 1873-3778. ; 1374, s. 254-260
-
Tidskriftsartikel (refereegranskat)abstract
- Abstract A chemometric approach is used for studying the combined effect of temperature, pressure and co-solvent fraction in analytical and preparative supercritical fluid chromatography (SFC). More specifically, by utilizing design of experiments coupled with careful measurements of the experimental conditions the interaction between pressure, temperature and co-solvent fraction was studied with respect to productivity, selectivity and retention in chiral SFC. A tris-(3,5-dimethylphenyl) carbamoyl cellulose stationary phase with carbon dioxide/methanol as mobile phase and the two racemic analytes trans-stilbene oxide (TSO) and 1,1′-bi-2-naphthol (BINOL) were investigated. It was found for the investigated model system that the co-solvent fraction and pressure were the parameters that most affected the retention factors and that the co-solvent fraction and column temperature were most important for controlling the selectivity. The productivity in the preparative mode of SFC was most influenced by the co-solvent fraction and temperature. Both high co-solvent fraction and temperature gave maximum productivity in the studied design space.
|
|
