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18 results on '"Larsson, P.T."'

7. Alpha- and beta-adrenergic influences on the tissue and urokinase plasminogen activator systems

Author

Larsson, P.T., Wallén, N.H., Wiman, B., Dooijewaard, G., and Gaubius instituut TNO

Subjects
isoprenaline, tissue plasminogen activator, drug potentiation, noradrenalin, urokinase, phentolamine, plasminogen activator inhibitor 1, adrenalin, human experiment, intravenous drug administration, male, dose response, heart rate, controlled study, fibrinolysis, propranolol, human, phentolamine mesylate
Abstract

Objective: To study the influence of α- and β-adrenoceptor stimulation in vivo on fibrinolysis in healthy male volunteers. Design: Infusions were given in a single blind fashion and in a randomized order if placebo infusions were included. Setting: University Department (Karolinska Hospital). Subjects: Thirty-four healthy, non-smoking male volunteers aged 21-38 years. Interventions: Study 1 - The volunteers participated in two or three separate experiments; 30 min infusions of saline placebo, phentolamine (500 μg/min) or propranolol (bolus dose of 140 μg/kg + 0.5 μg/kg/min) followed by the addition of a 30 min adrenaline infusion (0.4 nmol/kg/min), n=10 in each group. Study 2 - Infusion of a low and an intermediate-high dose of noradrenaline (0.15 and 0.75 nmol/kg/min; 20 min at each dose level), n=11. Study 3 - Infusion of a low and high dose of isoprenaline (5 and 20 ng/kg/min), each during 20 min, n=10. Main outcome measures: Venous plasma tissue plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1) antigen and activity levels, and plasma levels of urokinase (u-PA) antigen. Results: t-PA activity and antigen levels were markedly increased during adrenaline infusion (by 309±35 and 81±16% respectively, both P

Published
1999

9. Model films of cellulose II - Improved preparation method and characterization of the cellulose film

Author

Fält, Susanna, Wågberg, Lars, Vesterlind, Eva-Lotta, Larsson, P.T., Fält, Susanna, Wågberg, Lars, Vesterlind, Eva-Lotta, and Larsson, P.T.

Abstract

An optimization study of the preparation of spin-coated cellulose model films from the NMMO/DMSO system on silicon wafers has been made. The study shows that the cellulose concentration in the solution determines the cellulose film thickness and that the temperature of the solution affects the surface roughness. A lower solution temperature results in a lower surface roughness at cellulose concentrations below 0.8%. Using the described method, it is possible to prepare films with thicknesses of 30-90 nm with a constant surface roughness by changing the cellulose concentration, i.e. by dilution with DMSO. On these films, water has a contact angle less than 20degrees and about 50% of the material can, according to CP/MAS C-13-NMR spectroscopy on corresponding fibrous material, be considered to consist of crystalline cellulose II type material. It has further been shown that AFM can be used to determine the thickness of cellulose films, in both dry and wet states. In this method, the difference in height between the top surface and the underlying wafer has been measured at an incision made into the cellulose film. The cellulose films have also been spin-coated with the same technique as on the silicon oxide wafer onto the crystal in a quartz crystal microbalance (QCM). These model films were found to be suitable for swelling measurements with the QCM. The films were very stable during this type of measurement and films with different amounts of charges gave different swelling responses depending on their charges. As expected, films with a higher charge showed a higher swelling.

Published
2004

14. Model films of cellulose II – improved preparation method and characterization of the cellulose film.

Author

Fält, S., Wågberg, L., Vesterlind, E.-L., and Larsson, P.T.

Subjects
CELLULOSE, GLUCANS, POLYSACCHARIDES, SURFACE roughness, QUARTZ crystal microbalances, PIEZOELECTRIC devices
Abstract

An optimization study of the preparation of spin-coated cellulose model films from the NMMO/DMSO system on silicon wafers has been made. The study shows that the cellulose concentration in the solution determines the cellulose film thickness and that the temperature of the solution affects the surface roughness. A lower solution temperature results in a lower surface roughness at cellulose concentrations below 0.8%. Using the described method, it is possible to prepare films with thicknesses of 30-90 nm with a constant surface roughness by changing the cellulose concentration, i.e. by dilution with DMSO. On these films, water has a contact angle less than 200 and about 50% of the material can, according to CP/MAS 13C-NMR spectroscopy on corresponding fibrous material, be considered to consist of crystalline cellulose II type material. It has further been shown that AFM can be used to determine the thickness of cellulose films, in both dry and wet states. In this method, the difference in height between the top surface and the underlying wafer has been measured at an incision made into the cellulose film. The cellulose films have also been spin-coated with the same technique as on the silicon oxide wafer onto the crystal in a quartz crystal microbalance (QCM). These model films were found to be suitable for swelling measurements with the QCM. The films were very stable during this type of measurement and films with different amounts of charges gave different swelling responses depending on their charges. As expected, films with a higher charge showed a higher swelling. [ABSTRACT FROM AUTHOR]

Published
2004

15. A CP/MAS^1^3C NMR investigation of molecular ordering in celluloses

Author

Larsson, P.T., Wickholm, K., and Iversen, T.

Abstract

The individual states of order of cellulose found within Valonia, Cladophora, Halocynthia, cotton and wood cellulose were quantified by non-linear least-squares fitting of the ^1^3C NMR spectra. The results from the spectral fittings indicated that a cellulose form giving signals at @d 104.5 (C-1 region) and @d 88.1-88.5 (C-4 region) was present in all the investigated samples. Partial signal suppression by spin-lattice relaxation supported the findings from the spectral fittings. The spectral behavior of this cellulose form indicates it is a less-ordered or a para-crystalline 'in core' structure with a somewhat larger mobility than the crystalline cellulose I@a and I@b allomorphs.

Published
1997
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