Jan Karlsen - Academia.edu (original) (raw)
Papers by Jan Karlsen
Methods in Enzymology, Feb 1, 1997
... Permissions & Reprints. [8] Determination of thiamin and its phosphate esters in huma... more ... Permissions & Reprints. [8] Determination of thiamin and its phosphate esters in human blood, plasma, and urine. Chantal ME Tallaksen, Thomas Bøhmer, Jan Karlsen and Helge Bell. Available online 29 November 2003. Excerpt. Note: This is a one-page preview only. ...
Eur Food Res Technol, 1986
The photodecomposition of curcumin when exposed to UV/visible radiation is studied. The main degr... more The photodecomposition of curcumin when exposed to UV/visible radiation is studied. The main degradation products are identified. The reaction mechanisms are investigated and the order of the over-all degradation reactions and the half-lives of curcumin in different solvents and in the solid state are determined.
Eur Food Res Technol, 1991
1 Institute of Pharmacy, Department of Pharmaceutics, University of Oslo, PO Box 1068, Blindern, ... more 1 Institute of Pharmacy, Department of Pharmaceutics, University of Oslo, PO Box 1068, Blindern, N-0316 Oslo 3, Norway 2 Synthite Industrial Chemicals Ltd., Synthite Valley, Kolenchery 682311, India ... Studien fiber Curcumin und Curcuminoide XXI. Unterschiede des ...
Radiation Physics and Chemistry, Nov 1, 1999
The effects of gamma irradiation (25 kGy) as a sterilisation method for phospholipids (distearoyl... more The effects of gamma irradiation (25 kGy) as a sterilisation method for phospholipids (distearoylphosphatidylcholine and distearoylphosphatidylglycerol) were investigated. 31P-NMR revealed minor chemical degradation of the phospholipids but lower dynamic viscosity and pseudoplasticity, lower turbidity, higher diffusion constant, smaller size, more negative zeta potential and changes in the phase transition behaviour of the subsequently produced liposomes were observed. The observed changes could to some extent be explained by the irradiation-induced degradation products (distearoylphosphatidic acid, fatty acids, lysophospholipids).
International Journal of Pharmaceutics, May 1, 1991
Chloroquine has been reported to give toxic reactions which may be ascribed to the photochemical ... more Chloroquine has been reported to give toxic reactions which may be ascribed to the photochemical degradation of the substance. The effects of light at wavelengths of 240-600 nm on solutions of chloroquine in isopropanol, and of light at wavelengths of 320-600 nm on solutions of chloroquine in buffer solutions were investigated. Seven of the photochemical decomposition products of chloroquine were isolated and identified by mass-spectrometry (El, CI and high-resolution MS) and nuclear magnetic resonance spectroscopy (1H-NMR).
Acta Chemica Scandinavica
Acta Chemica Scandinavica, 1983
Radiation Physics and Chemistry, 1999
The effects of gamma irradiation (25 kGy) as a sterilisation method for phospholipids (distearoyl... more The effects of gamma irradiation (25 kGy) as a sterilisation method for phospholipids (distearoylphosphatidylcholine and distearoylphosphatidylglycerol) were investigated. 31P-NMR revealed minor chemical degradation of the phospholipids but lower dynamic viscosity and pseudoplasticity, lower turbidity, higher diffusion constant, smaller size, more negative zeta potential and changes in the phase transition behaviour of the subsequently produced liposomes were observed. The observed changes could to some extent be explained by the irradiation-induced degradation products (distearoylphosphatidic acid, fatty acids, lysophospholipids).
Micron and Microscopica Acta, 1991
International Contact Lens Clinic, 1997
International Journal of Management and Enterprise Development, 2006
... During the last decades several guidelines have been published presenting rules for what to f... more ... During the last decades several guidelines have been published presenting rules for what to focus on to ... Standish Group observed that an IT project has a higher chance of being a success if the ... This supports the factor leadership and managerial skills of the project manager. ...
![Research paper thumbnail of [8] Determination of thiamin and its phosphate esters in human blood, plasma, and urine](https://attachments.academia-assets.com/43110106/thumbnails/1.jpg)
](Methods in Enzymology, 1997
International Journal of Pharmaceutics, 1993
... An increase in lipid peroxidation could only be observed in sam-ples without curcumin. ... Pa... more ... An increase in lipid peroxidation could only be observed in sam-ples without curcumin. ... Pabon, HJJ, A synthesis of curcumin and related com-pounds. Rec. ... Yu, MJ, McCowan, JR, Bertsch, B. and Ho, PPK, En-zymic and Nonenzymic Lipid Peroxidation: Inhibition by Substitutes ...
International Journal of Pharmaceutics, 1995
ABSTRACT A new dialysis method was designed with the purpose of studying drug release rate from l... more ABSTRACT A new dialysis method was designed with the purpose of studying drug release rate from liposomes. The liposomes were diluted directly in the continuous phase and dialysed against a small volume of buffer. The dialysate was changed at 10 min intervals and the amount of carboxyfluorescein released was calculated from a standard curve. To evaluate the new method, parallel measurements were recorded with the traditional carboxyfluorescein assay, which is based on direct measurements on liposomes containing a self-quenching concentration. The new method is called fractional dialysis, and is shown to have sensitivity similar to that of the carboxyfluorescein assay. In certain cases the fractional dialysis method gives a more accurate release profile. It is suggested that fractional dialysis can be a useful alternative to other techniques for recording the in vitro release characteristics of specific drugs from liposomes or other colloidal carriers.
International Journal of Pharmaceutics, 1997
The' interaction between liposomes and chitosan has been described in an earlier paper. In the pr... more The' interaction between liposomes and chitosan has been described in an earlier paper. In the present work, the production of liposome-chitosan complexes (Chitosomes) was further studied using factorial designs. The parameters studied were the stirring rate, rate of addition of liposomes to polymer, ionic strength, chitosan quality, lipid/polymer ratio and pH. Particle size, polydispersity and charge were the measured parameters. Cryo-electron microscopy was used for further study of one of the combinations. It was found that the ionic strength, chitosan quality, lipid/polymer ratio and pH had a significant effect on the resulting aggregate size. The leakage of quinine from Chitosomes was compared to the leakage from liposomes using a fractional dialysis method. The leakage rates were similar, but the Chitosomes produced a higher initial release and showed less scattering of the data. Measurements of zeta potential indicated adsorption of quinine to the liposomal membrane. Chitosomes could be stored in a refrigerator for at least 6 months without significant change in particle size. © 1997 Elsevier Science B.V.
International Journal of Pharmaceutics, 1988
... Stabilization of photolabile drugs in serum samples by addition of curcumin Hanne Hjorth Tenn... more ... Stabilization of photolabile drugs in serum samples by addition of curcumin Hanne Hjorth Tennesen and Jan Karlsen Institute of Pharmacy, University of Oslo ... in serum under the influence of daylight is reported to be between 44 min and 2.7 h (Bach, 1983; Hamann and McAllister ...
International Journal of Pharmaceutics, 1994
... Alamelu, S. and Panduranga Rao, K., Studies on the car-boxymethyl chitosan-containing liposom... more ... Alamelu, S. and Panduranga Rao, K., Studies on the car-boxymethyl chitosan-containing liposomes for their stabil-ity and controlled release of ... Klein, JW, Ware, BR, Barclay, G. and Petty, HR, Phos-pholipid dependence of calcium ion effects on elec-trophoretic mobilities of ...
Journal of chromatography, Jan 8, 1991
A high-performance liquid chromatographic method for the simultaneous determination of thiamin an... more A high-performance liquid chromatographic method for the simultaneous determination of thiamin and thiamin phosphate esters in human blood or serum has been developed. The eluent consists of acetonitrile and phosphate buffer, in the ratios 90:10 (v/v) for the elution of thiamine and 60:40 (v/v) for the phosphate esters. The four compounds are eluted within 15 min. The detection limit is 13-16 fmol. Between-assay variation is 5-11%. Samples of whole blood and serum from 30 healthy adults were analysed. The following reference values were obtained for 15 females 15 males (nM, mean +/- S.D.). In serum: thiamin, 10.9 +/- 2.9/16.9 +/- 3.3; thiamin monophosphate, 8.3 +/- 1.5/3.7 +/- 1.5. In whole blood: thiamin, 29.6 +/- 10.0/33.4 +/- 10.4; thiamin monophosphate, 9.7 +/- 2.3/10.9 +/- 5.1; thiamin diphosphate, 121 +/- 29.6/165 +/- 40.4.
Nuclear Medicine Communications, 2006
Internal radiotherapy requires the localization of the radionuclide to the site of action. A new ... more Internal radiotherapy requires the localization of the radionuclide to the site of action. A new injectable alginate gel formulation intended to undergo immediate gelation in tissues and capable of encapsulating radioactive particles containing 90Y was investigated. The formulation was injected intramuscularly, into the bone marrow compartment of the femur and intravenously, respectively, in pigs. The distribution of radioactivity in various tissues was determined. Following intramuscular injection, more than 90% of the radioactivity was found at the site of injection. Following injection into bone marrow, 30-40% of the radioactivity was retained at the site of injection, but a considerable amount of radioactivity was also detected in the lungs (35-45%) and the liver (5-18%). Following intravenous injection, 80-90% of the radioactivity was found in the lungs. The present formulation appears suitable for localized radiotherapy in organs and tissues having low perfusion.
Methods in Enzymology, Feb 1, 1997
... Permissions & Reprints. [8] Determination of thiamin and its phosphate esters in huma... more ... Permissions & Reprints. [8] Determination of thiamin and its phosphate esters in human blood, plasma, and urine. Chantal ME Tallaksen, Thomas Bøhmer, Jan Karlsen and Helge Bell. Available online 29 November 2003. Excerpt. Note: This is a one-page preview only. ...
Eur Food Res Technol, 1986
The photodecomposition of curcumin when exposed to UV/visible radiation is studied. The main degr... more The photodecomposition of curcumin when exposed to UV/visible radiation is studied. The main degradation products are identified. The reaction mechanisms are investigated and the order of the over-all degradation reactions and the half-lives of curcumin in different solvents and in the solid state are determined.
Eur Food Res Technol, 1991
1 Institute of Pharmacy, Department of Pharmaceutics, University of Oslo, PO Box 1068, Blindern, ... more 1 Institute of Pharmacy, Department of Pharmaceutics, University of Oslo, PO Box 1068, Blindern, N-0316 Oslo 3, Norway 2 Synthite Industrial Chemicals Ltd., Synthite Valley, Kolenchery 682311, India ... Studien fiber Curcumin und Curcuminoide XXI. Unterschiede des ...
Radiation Physics and Chemistry, Nov 1, 1999
The effects of gamma irradiation (25 kGy) as a sterilisation method for phospholipids (distearoyl... more The effects of gamma irradiation (25 kGy) as a sterilisation method for phospholipids (distearoylphosphatidylcholine and distearoylphosphatidylglycerol) were investigated. 31P-NMR revealed minor chemical degradation of the phospholipids but lower dynamic viscosity and pseudoplasticity, lower turbidity, higher diffusion constant, smaller size, more negative zeta potential and changes in the phase transition behaviour of the subsequently produced liposomes were observed. The observed changes could to some extent be explained by the irradiation-induced degradation products (distearoylphosphatidic acid, fatty acids, lysophospholipids).
International Journal of Pharmaceutics, May 1, 1991
Chloroquine has been reported to give toxic reactions which may be ascribed to the photochemical ... more Chloroquine has been reported to give toxic reactions which may be ascribed to the photochemical degradation of the substance. The effects of light at wavelengths of 240-600 nm on solutions of chloroquine in isopropanol, and of light at wavelengths of 320-600 nm on solutions of chloroquine in buffer solutions were investigated. Seven of the photochemical decomposition products of chloroquine were isolated and identified by mass-spectrometry (El, CI and high-resolution MS) and nuclear magnetic resonance spectroscopy (1H-NMR).
Acta Chemica Scandinavica
Acta Chemica Scandinavica, 1983
Radiation Physics and Chemistry, 1999
The effects of gamma irradiation (25 kGy) as a sterilisation method for phospholipids (distearoyl... more The effects of gamma irradiation (25 kGy) as a sterilisation method for phospholipids (distearoylphosphatidylcholine and distearoylphosphatidylglycerol) were investigated. 31P-NMR revealed minor chemical degradation of the phospholipids but lower dynamic viscosity and pseudoplasticity, lower turbidity, higher diffusion constant, smaller size, more negative zeta potential and changes in the phase transition behaviour of the subsequently produced liposomes were observed. The observed changes could to some extent be explained by the irradiation-induced degradation products (distearoylphosphatidic acid, fatty acids, lysophospholipids).
Micron and Microscopica Acta, 1991
International Contact Lens Clinic, 1997
International Journal of Management and Enterprise Development, 2006
... During the last decades several guidelines have been published presenting rules for what to f... more ... During the last decades several guidelines have been published presenting rules for what to focus on to ... Standish Group observed that an IT project has a higher chance of being a success if the ... This supports the factor leadership and managerial skills of the project manager. ...
Methods in Enzymology, 1997
International Journal of Pharmaceutics, 1993
... An increase in lipid peroxidation could only be observed in sam-ples without curcumin. ... Pa... more ... An increase in lipid peroxidation could only be observed in sam-ples without curcumin. ... Pabon, HJJ, A synthesis of curcumin and related com-pounds. Rec. ... Yu, MJ, McCowan, JR, Bertsch, B. and Ho, PPK, En-zymic and Nonenzymic Lipid Peroxidation: Inhibition by Substitutes ...
International Journal of Pharmaceutics, 1995
ABSTRACT A new dialysis method was designed with the purpose of studying drug release rate from l... more ABSTRACT A new dialysis method was designed with the purpose of studying drug release rate from liposomes. The liposomes were diluted directly in the continuous phase and dialysed against a small volume of buffer. The dialysate was changed at 10 min intervals and the amount of carboxyfluorescein released was calculated from a standard curve. To evaluate the new method, parallel measurements were recorded with the traditional carboxyfluorescein assay, which is based on direct measurements on liposomes containing a self-quenching concentration. The new method is called fractional dialysis, and is shown to have sensitivity similar to that of the carboxyfluorescein assay. In certain cases the fractional dialysis method gives a more accurate release profile. It is suggested that fractional dialysis can be a useful alternative to other techniques for recording the in vitro release characteristics of specific drugs from liposomes or other colloidal carriers.
International Journal of Pharmaceutics, 1997
The' interaction between liposomes and chitosan has been described in an earlier paper. In the pr... more The' interaction between liposomes and chitosan has been described in an earlier paper. In the present work, the production of liposome-chitosan complexes (Chitosomes) was further studied using factorial designs. The parameters studied were the stirring rate, rate of addition of liposomes to polymer, ionic strength, chitosan quality, lipid/polymer ratio and pH. Particle size, polydispersity and charge were the measured parameters. Cryo-electron microscopy was used for further study of one of the combinations. It was found that the ionic strength, chitosan quality, lipid/polymer ratio and pH had a significant effect on the resulting aggregate size. The leakage of quinine from Chitosomes was compared to the leakage from liposomes using a fractional dialysis method. The leakage rates were similar, but the Chitosomes produced a higher initial release and showed less scattering of the data. Measurements of zeta potential indicated adsorption of quinine to the liposomal membrane. Chitosomes could be stored in a refrigerator for at least 6 months without significant change in particle size. © 1997 Elsevier Science B.V.
International Journal of Pharmaceutics, 1988
... Stabilization of photolabile drugs in serum samples by addition of curcumin Hanne Hjorth Tenn... more ... Stabilization of photolabile drugs in serum samples by addition of curcumin Hanne Hjorth Tennesen and Jan Karlsen Institute of Pharmacy, University of Oslo ... in serum under the influence of daylight is reported to be between 44 min and 2.7 h (Bach, 1983; Hamann and McAllister ...
International Journal of Pharmaceutics, 1994
... Alamelu, S. and Panduranga Rao, K., Studies on the car-boxymethyl chitosan-containing liposom... more ... Alamelu, S. and Panduranga Rao, K., Studies on the car-boxymethyl chitosan-containing liposomes for their stabil-ity and controlled release of ... Klein, JW, Ware, BR, Barclay, G. and Petty, HR, Phos-pholipid dependence of calcium ion effects on elec-trophoretic mobilities of ...
Journal of chromatography, Jan 8, 1991
A high-performance liquid chromatographic method for the simultaneous determination of thiamin an... more A high-performance liquid chromatographic method for the simultaneous determination of thiamin and thiamin phosphate esters in human blood or serum has been developed. The eluent consists of acetonitrile and phosphate buffer, in the ratios 90:10 (v/v) for the elution of thiamine and 60:40 (v/v) for the phosphate esters. The four compounds are eluted within 15 min. The detection limit is 13-16 fmol. Between-assay variation is 5-11%. Samples of whole blood and serum from 30 healthy adults were analysed. The following reference values were obtained for 15 females 15 males (nM, mean +/- S.D.). In serum: thiamin, 10.9 +/- 2.9/16.9 +/- 3.3; thiamin monophosphate, 8.3 +/- 1.5/3.7 +/- 1.5. In whole blood: thiamin, 29.6 +/- 10.0/33.4 +/- 10.4; thiamin monophosphate, 9.7 +/- 2.3/10.9 +/- 5.1; thiamin diphosphate, 121 +/- 29.6/165 +/- 40.4.
Nuclear Medicine Communications, 2006
Internal radiotherapy requires the localization of the radionuclide to the site of action. A new ... more Internal radiotherapy requires the localization of the radionuclide to the site of action. A new injectable alginate gel formulation intended to undergo immediate gelation in tissues and capable of encapsulating radioactive particles containing 90Y was investigated. The formulation was injected intramuscularly, into the bone marrow compartment of the femur and intravenously, respectively, in pigs. The distribution of radioactivity in various tissues was determined. Following intramuscular injection, more than 90% of the radioactivity was found at the site of injection. Following injection into bone marrow, 30-40% of the radioactivity was retained at the site of injection, but a considerable amount of radioactivity was also detected in the lungs (35-45%) and the liver (5-18%). Following intravenous injection, 80-90% of the radioactivity was found in the lungs. The present formulation appears suitable for localized radiotherapy in organs and tissues having low perfusion.