Terje Vasskog - Academia.edu (original) (raw)

Papers by Terje Vasskog

European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences, Jan 31, 2015

A prerequisite for successful oral drug therapy is the drug's ability to cross the gastrointe... more A prerequisite for successful oral drug therapy is the drug's ability to cross the gastrointestinal barrier. Considering the increasing number of new chemical entities in modern drug discovery, reliable and fast in vitro models are required for early and efficient prediction of intestinal permeability. To mimic the intestinal environment, use of biorelevant media may provide valuable information on in vivo drug permeation. The present study aims at improving the novel biomimetic phospholipid vesicle-based permeation assay's (PVPAbiomimetic) biorelevance by investigating the applicability of the biorelevant media; fasted state simulated intestinal fluid (FaSSIF) and fed state simulated intestinal fluid (FeSSIF). The FaSSIF and FeSSIF's influence on the permeability of the model drugs acyclovir, indomethacin, griseofulvin and nadolol was then assessed. The barriers' robustness in terms of storage stability was also evaluated. The barriers were found to maintain their i...

Environmental Sciences Europe, 2015

ABSTRACT Results: All the SSRIs had a significant concentration reduction during the aeration tre... more ABSTRACT Results: All the SSRIs had a significant concentration reduction during the aeration treatment process. Total SSRI concentrations were reduced significantly during aerobic treatment, and the individual SSRIs were reduced by 89% to 100% after 120 h. Among the high-concentration samples, fluoxetine (10 mg L-1 ) was the least degraded with 93% concentration reduction. Among the low-concentration samples, paroxetine was the least degraded with 89% concentration reduction. Fluvoxamine and citalopram were most effectively eliminated and were completely removed from both the high- and low-concentration samples. The samples were also investigated for the metabolites desmethylcitalopram, didesmethylcitalopram and norfluoxetine but only norfluoxetine in the high-concentration fluoxetine sample was detected.

Waste Management, 2009

Sewage and sewage sludge is known to contain pharmaceuticals, and since sewage sludge is often us... more Sewage and sewage sludge is known to contain pharmaceuticals, and since sewage sludge is often used as fertilizer within agriculture, the reduction of the selective serotonin reuptake inhibitors (SSRIs) Citalopram, Sertraline, Paroxetine, Fluvoxamine and Fluoxetine during composting has been investigated. Sewage sludge was spiked with the SSRIs before the composting experiment started, and the concentration of the SSRIs in the sludge during a 21 day composting period was measured by liquid phase microextraction (LPME) and high-performance liquid chromatography-mass spectrometry. All the SSRIs had a significant decrease in concentration during the composting process. The highest reduction rates were measured for Fluoxetine and Paroxetine and the lowest for Citalopram. In addition three out of four known SSRI metabolites were found in all the samples, and two of them showed a significant increase in concentration during the composting period.

Molecular Immunology, 2009

Marine invertebrates are a rich source for the discovery of novel antimicrobial peptides, compoun... more Marine invertebrates are a rich source for the discovery of novel antimicrobial peptides, compounds regarded as important defense components in the host defense system. Here we report the purification and characterization of an 11.7kDa Gly-rich peptide, named hyastatin, from the hemocytes of Hyas araneus. It consists of three distinctly different domains: an N-terminal region enriched in Gly residues, a short Pro/Arg-rich region, and a C-terminal region containing six Cys residues with a Cys pattern resembling the one found in penaeidins. The C-terminus of the mature peptide is presumably amidated. The hyastatin transcript is constitutively expressed and mainly found in hemocytes. Hyastatin shows antimicrobial activity against yeasts, and Gram-positive and Gram-negative bacteria. The N-terminal region, devoid of the Cys-containing region, was recombinantly expressed in Escherichia coli cells, and shows only weak activity against the Gram-positive bacteria Corynebacterium glutamicum. Both hyastatin and the N-terminal region had the ability to bind chitin. Conclusively, this indicates the importance of the Cys-containing region for the antimicrobial activity, and a possible multifunctional character of hyastatin.

Journal of Chromatography A, 2006

An analytical method for quantification of the selective serotonin reuptake inhibitors (SSRIs) ci... more An analytical method for quantification of the selective serotonin reuptake inhibitors (SSRIs) citalopram, sertraline, paroxetine, fluoxetine and fluvoxamine in sewage influents and effluents from selected sewage treatment plants (STPs) has been developed and validated. This quantification method is based on solid phase extraction of 2.5 L samples, followed by liquid-liquid extraction for further sample clean up in order to minimize matrix effects during subsequent quantification. The samples were analysed on a high performance liquid chromatograph coupled to a triple quadrupole mass spectrometric detector using 0.1% ammonia in acetonitrile/water as mobile phase, with positive electrospray ionisation and multiple reaction monitoring for detection and quantification. 1-[3-(10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5-ylidene)propyl]-pyrrolidine (N-7084) was used as internal standard for quantification. The recovery rates of the SSRIs ranged between 54 and 84%, and the method limit of quantification (MLQ) was between 120 and 290 pg/L for the target compounds. Samples were collected in July 2005 from three different STPs and a pump station in Tromsø, Northern Norway. Two of the STPs serve the University hospital and its psychiatric department, respectively, in addition to domestic sewage. SSRIs were detected in all samples collected. The concentrations varied greatly from below the MLQ to several hundreds ng/L. Concentrations in influents were higher compared to filtered effluents, indicating that SSRIs adsorb to particulate matter, are degraded by microorganisms, or degraded in other ways during the filtration process. However, more samples should be analysed before general conclusions can be drawn.

Journal of Chromatography A, 2008

A method for the determination of five selective serotonin reuptake inhibitors (citalopram, sertr... more A method for the determination of five selective serotonin reuptake inhibitors (citalopram, sertraline, fluoxetine, fluvoxamine and paroxetine) and four of their metabolites (desmethylcitalopram, didesmethylcitalopram, norfluoxetine and desmethylsertraline) in seawater and sewage influents and effluents, has been developed and validated. The method is based on a three-phase hollow-fibre supported liquid phase microextraction of 1.1 L samples, followed by high performance liquid chromatography with electrospray ionization and mass spectrometric detection. The detection limits varied between 17 pg/L (citalopram) and 618 ng/L (desmethylsertraline), and the quantification limits between 57 pg/L (citalopram) and 4.1 ng/L (desmethylsertraline). Sampling was done from February to August in 2007 on three different locations with dissimilarities concerning waste water treatment procedures. No significant difference in SSRI cleansing efficiency between merely sieving (Langnes STP, Tromsø) and a more advanced sewage treatment (VEAS STP, Oslo) was seen. All the investigated compounds are present in all waste water samples from these STPs, and a total concentration of SSRIs and metabolites up to 840 ng/L has been found. Untreated sewage samples have been collected in the small town Longyearbyen at Spitsbergen. Despite few inhabitants , it was still possible to find traces of SSRIs in the waste water. In Tromsø and Longyearbyen the waste water is discharged into the sea, therefore seawater samples have been collected close to the outlets. The results show higher concentrations of SSRIs outside Longyearbyen than Tromsø, possibly due to the stronger tidal currents around Tromsø. However, the concentrations are quite low, not exceeding total concentrations of 3 ng/L. .no (T. Vasskog). inhibitors (SSRIs) are a relatively new group of antidepressants. The five SSRIs citalopram, paroxetine, fluoxetine, fluvoxamine and sertraline were introduced to the Norwegian market in the first half of the 1990s. They quickly became popular, probably due to a better side-effect profile than the traditional tricyclic antidepressants. Today they amount to a large part of the worlds' consume of antidepressants, and in Norway 4% of the inhabitants are treated with one of the SSRIs [4,. Earlier studies have shown that SSRIs have adverse effects on non-target organisms, although in higher concentrations than expected to be found in nature .

European Journal of Pharmaceutical Sciences, 2007

Liposomes Phospholipids Phase transition pH Differential scanning calorimetry DSC Shaking Stirrin... more Liposomes Phospholipids Phase transition pH Differential scanning calorimetry DSC Shaking Stirring Membrane interactions Bilayer Drug permeability a b s t r a c t Recently, we reported on the development and structural characterization of a phospholipid vesicle based barrier useful for medium throughput screening of passive drug permeability.

Journal of Pharmaceutical and Biomedical Analysis, 2010

Particle size 23 a b s t r a c t

European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences, Jan 31, 2015

A prerequisite for successful oral drug therapy is the drug's ability to cross the gastrointe... more A prerequisite for successful oral drug therapy is the drug's ability to cross the gastrointestinal barrier. Considering the increasing number of new chemical entities in modern drug discovery, reliable and fast in vitro models are required for early and efficient prediction of intestinal permeability. To mimic the intestinal environment, use of biorelevant media may provide valuable information on in vivo drug permeation. The present study aims at improving the novel biomimetic phospholipid vesicle-based permeation assay's (PVPAbiomimetic) biorelevance by investigating the applicability of the biorelevant media; fasted state simulated intestinal fluid (FaSSIF) and fed state simulated intestinal fluid (FeSSIF). The FaSSIF and FeSSIF's influence on the permeability of the model drugs acyclovir, indomethacin, griseofulvin and nadolol was then assessed. The barriers' robustness in terms of storage stability was also evaluated. The barriers were found to maintain their i...

Environmental Sciences Europe, 2015

ABSTRACT Results: All the SSRIs had a significant concentration reduction during the aeration tre... more ABSTRACT Results: All the SSRIs had a significant concentration reduction during the aeration treatment process. Total SSRI concentrations were reduced significantly during aerobic treatment, and the individual SSRIs were reduced by 89% to 100% after 120 h. Among the high-concentration samples, fluoxetine (10 mg L-1 ) was the least degraded with 93% concentration reduction. Among the low-concentration samples, paroxetine was the least degraded with 89% concentration reduction. Fluvoxamine and citalopram were most effectively eliminated and were completely removed from both the high- and low-concentration samples. The samples were also investigated for the metabolites desmethylcitalopram, didesmethylcitalopram and norfluoxetine but only norfluoxetine in the high-concentration fluoxetine sample was detected.

Waste Management, 2009

Sewage and sewage sludge is known to contain pharmaceuticals, and since sewage sludge is often us... more Sewage and sewage sludge is known to contain pharmaceuticals, and since sewage sludge is often used as fertilizer within agriculture, the reduction of the selective serotonin reuptake inhibitors (SSRIs) Citalopram, Sertraline, Paroxetine, Fluvoxamine and Fluoxetine during composting has been investigated. Sewage sludge was spiked with the SSRIs before the composting experiment started, and the concentration of the SSRIs in the sludge during a 21 day composting period was measured by liquid phase microextraction (LPME) and high-performance liquid chromatography-mass spectrometry. All the SSRIs had a significant decrease in concentration during the composting process. The highest reduction rates were measured for Fluoxetine and Paroxetine and the lowest for Citalopram. In addition three out of four known SSRI metabolites were found in all the samples, and two of them showed a significant increase in concentration during the composting period.

Molecular Immunology, 2009

Marine invertebrates are a rich source for the discovery of novel antimicrobial peptides, compoun... more Marine invertebrates are a rich source for the discovery of novel antimicrobial peptides, compounds regarded as important defense components in the host defense system. Here we report the purification and characterization of an 11.7kDa Gly-rich peptide, named hyastatin, from the hemocytes of Hyas araneus. It consists of three distinctly different domains: an N-terminal region enriched in Gly residues, a short Pro/Arg-rich region, and a C-terminal region containing six Cys residues with a Cys pattern resembling the one found in penaeidins. The C-terminus of the mature peptide is presumably amidated. The hyastatin transcript is constitutively expressed and mainly found in hemocytes. Hyastatin shows antimicrobial activity against yeasts, and Gram-positive and Gram-negative bacteria. The N-terminal region, devoid of the Cys-containing region, was recombinantly expressed in Escherichia coli cells, and shows only weak activity against the Gram-positive bacteria Corynebacterium glutamicum. Both hyastatin and the N-terminal region had the ability to bind chitin. Conclusively, this indicates the importance of the Cys-containing region for the antimicrobial activity, and a possible multifunctional character of hyastatin.

Journal of Chromatography A, 2006

An analytical method for quantification of the selective serotonin reuptake inhibitors (SSRIs) ci... more An analytical method for quantification of the selective serotonin reuptake inhibitors (SSRIs) citalopram, sertraline, paroxetine, fluoxetine and fluvoxamine in sewage influents and effluents from selected sewage treatment plants (STPs) has been developed and validated. This quantification method is based on solid phase extraction of 2.5 L samples, followed by liquid-liquid extraction for further sample clean up in order to minimize matrix effects during subsequent quantification. The samples were analysed on a high performance liquid chromatograph coupled to a triple quadrupole mass spectrometric detector using 0.1% ammonia in acetonitrile/water as mobile phase, with positive electrospray ionisation and multiple reaction monitoring for detection and quantification. 1-[3-(10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5-ylidene)propyl]-pyrrolidine (N-7084) was used as internal standard for quantification. The recovery rates of the SSRIs ranged between 54 and 84%, and the method limit of quantification (MLQ) was between 120 and 290 pg/L for the target compounds. Samples were collected in July 2005 from three different STPs and a pump station in Tromsø, Northern Norway. Two of the STPs serve the University hospital and its psychiatric department, respectively, in addition to domestic sewage. SSRIs were detected in all samples collected. The concentrations varied greatly from below the MLQ to several hundreds ng/L. Concentrations in influents were higher compared to filtered effluents, indicating that SSRIs adsorb to particulate matter, are degraded by microorganisms, or degraded in other ways during the filtration process. However, more samples should be analysed before general conclusions can be drawn.

Journal of Chromatography A, 2008

A method for the determination of five selective serotonin reuptake inhibitors (citalopram, sertr... more A method for the determination of five selective serotonin reuptake inhibitors (citalopram, sertraline, fluoxetine, fluvoxamine and paroxetine) and four of their metabolites (desmethylcitalopram, didesmethylcitalopram, norfluoxetine and desmethylsertraline) in seawater and sewage influents and effluents, has been developed and validated. The method is based on a three-phase hollow-fibre supported liquid phase microextraction of 1.1 L samples, followed by high performance liquid chromatography with electrospray ionization and mass spectrometric detection. The detection limits varied between 17 pg/L (citalopram) and 618 ng/L (desmethylsertraline), and the quantification limits between 57 pg/L (citalopram) and 4.1 ng/L (desmethylsertraline). Sampling was done from February to August in 2007 on three different locations with dissimilarities concerning waste water treatment procedures. No significant difference in SSRI cleansing efficiency between merely sieving (Langnes STP, Tromsø) and a more advanced sewage treatment (VEAS STP, Oslo) was seen. All the investigated compounds are present in all waste water samples from these STPs, and a total concentration of SSRIs and metabolites up to 840 ng/L has been found. Untreated sewage samples have been collected in the small town Longyearbyen at Spitsbergen. Despite few inhabitants , it was still possible to find traces of SSRIs in the waste water. In Tromsø and Longyearbyen the waste water is discharged into the sea, therefore seawater samples have been collected close to the outlets. The results show higher concentrations of SSRIs outside Longyearbyen than Tromsø, possibly due to the stronger tidal currents around Tromsø. However, the concentrations are quite low, not exceeding total concentrations of 3 ng/L. .no (T. Vasskog). inhibitors (SSRIs) are a relatively new group of antidepressants. The five SSRIs citalopram, paroxetine, fluoxetine, fluvoxamine and sertraline were introduced to the Norwegian market in the first half of the 1990s. They quickly became popular, probably due to a better side-effect profile than the traditional tricyclic antidepressants. Today they amount to a large part of the worlds' consume of antidepressants, and in Norway 4% of the inhabitants are treated with one of the SSRIs [4,. Earlier studies have shown that SSRIs have adverse effects on non-target organisms, although in higher concentrations than expected to be found in nature .

European Journal of Pharmaceutical Sciences, 2007

Liposomes Phospholipids Phase transition pH Differential scanning calorimetry DSC Shaking Stirrin... more Liposomes Phospholipids Phase transition pH Differential scanning calorimetry DSC Shaking Stirring Membrane interactions Bilayer Drug permeability a b s t r a c t Recently, we reported on the development and structural characterization of a phospholipid vesicle based barrier useful for medium throughput screening of passive drug permeability.

Journal of Pharmaceutical and Biomedical Analysis, 2010

Particle size 23 a b s t r a c t