| 1. |
- Wolk, A, et al.
(författare)
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Self-administered food frequency questionnaire : the effect of different designs on food and nutrient intake estimates
- 1994
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Ingår i: International Journal of Epidemiology. - : Oxford University Press (OUP). - 0300-5771 .- 1464-3685. ; 23:3, s. 570-6
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Our objective was to determine the possible influence that different designs of a food frequency questionnaire might have on food, energy and nutrient intake estimates.METHODS: A population-based survey included 6783 women, 40-70 years old, living in central Sweden. Using a factorial study design, we compared eight different types of questionnaire covering combinations of three factors: increasing/decreasing frequency categories; addition of portion sizes; and addition of non-dietary questions. All questionnaires included the same list of 60 food items. One of the eight questionnaires was mailed to each subject according to a random assignment. The overall response rate was 77%.RESULTS: Compared with increasing frequencies, decreasing order of frequency categories entailed 3-11% higher estimates of mean intake for 7 of 14 food groups, 4% higher estimates for energy and 3-6% higher estimates for 13 of 18 nutrients. Addition of portion sizes had heterogeneous effects, both on dietary items (e.g. from -30% decrease for eggs to +76% increase for coffee) and on calculated nutrients (from -7% for beta-carotene to +19% for vitamin C). The inclusion of some additional non-dietary questions did not influence the estimated mean intake of any food or nutrient.CONCLUSIONS: The results of this study have implications for the design of questionnaires and for pooled analyses in nutritional epidemiology, when different food questionnaires are used.
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| 2. |
- Bergström, Erik, et al.
(författare)
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Dietary changes in Swedish adolescents.
- 1993
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Ingår i: Acta Paediatrica. - 0803-5253 .- 1651-2227. ; 82:5, s. 472-80
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Tidskriftsartikel (refereegranskat)abstract
- A school-based dietary survey, using seven-day records, was performed in two cohorts of Swedish adolescents; 14- and 17-year-olds. The study comprised 366 boys and 365 girls. When compared to previous studies in Sweden, a striking finding was a decrease in dietary fat intake and an increase in carbohydrate intake. However, the relative intake of saturated fat had not changed (15% of total energy). The dietary change was mainly due to an increased consumption of cereal products. There were no major differences in dietary habits or nutrient density of the food between the two age groups, or between boys and girls. The mean intakes of protein, fat and carbohydrate, expressed as a percentage of the total energy intake, were 15, 33 and 52%, respectively. The mean intakes of vitamins and minerals were low only for selenium. The boys had a high iron intake (1.5 and 1.7 times the recommended intake for 14- and 17-year-olds, respectively) while the mean iron intake for girls was 0.9 times the recommended dietary allowances in both age groups. The intake of dietary salt was higher in boys than in girls (7.7 g and 9.0 g per day in 14- and 17-year-old boys, respectively, and 5.8 g per day in both 14- and 17-year-old girls). In a long-term health perspective, this positive change in nutrient intake in adolescents may contribute to a reduction in the incidence of diet-related diseases in Sweden.(ABSTRACT TRUNCATED AT 250 WORDS)
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| 3. |
- Bergström, L
(författare)
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Characterization of the surface chemistry of silicon nitride powders
- 1994
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Ingår i: Ceramic Transactions. - : American Ceramic Society. ; , s. 77-87
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Bokkapitel (refereegranskat)abstract
- Introduction: Silicon nitride is a ceramic material with a potential for high strength at room as well as elevated temperatures, good thermal shock resistance and relatively good oxidation resistance. However, optimal properties can only be realized when the microstructure and the grain boundary composition of the sintered body is controlled. Several studies have shown that the surface properties of the starting powder, together with the choice and addition of sintering aids, play a decisive role in determining the final properties [1-3]. However, the final properties of the sintered material depend on many different parameters. These parameters include the green-body characteristics, the physical and bulk chemical powder properties and the sintering conditions together with the powder surface chemical properties. Hence, it has been difficult to define the relationship between only the surface chemical properties and materials properties more precisely. Also, it is not clear how the relevant surface properties of silicon nitride should be characterized and quantified. This paper is a part of a review on the surface chemistry of silicon nitride [4]. The focus will be on an overview of the methods that are available to characterize relevant surface properties of ceramic powders, together with a summary on the present understanding of the surface chemistry of silicon nitride.
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| 4. |
- Bergström, L, et al.
(författare)
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Consolidation behavior of flocculated alumina suspensions
- 1992
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Ingår i: Journal of The American Ceramic Society. - 0002-7820 .- 1551-2916. ; 75, s. 3305-3314
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Tidskriftsartikel (refereegranskat)abstract
- The consolidation behavior of flocculated alumina suspensions was analyzed as a function of the interparticle energy. Consolidation was performed by a centrifugal force field or by gravity and both the time dependent and equilibrium density profiles were measured by a gamma ray absorption technique. The interparticle energy at contact was controlled by adsorbing fatty acids of varying molecular weight at the alumina/decalin interface. We found that strongly attractive interactions result in a particle network which resists consolidation and shows compressible behavior over a large stress range. The most weakly flocculated suspension showed an essentially incompressible, homogeneous density profile after consolidation at different centrifugal speeds. We also found a significant variation in the maximum volume fraction, m, obtained, with m 0.54 for the most strongly flocculated suspension to m 0.63 for the most weakly flocculated suspension. The compressive yield stresses show a behavior which can be fitted to a modified power law. In this paper, we discuss possible correlations between the fitting parameters and physical properties of the flocculated suspensions.
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| 5. |
- Bergström, L
(författare)
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Rheology of concentrated suspensions
- 1994
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Ingår i: Surface and Colloid Chemistry in Advanced Ceramics Processing. - : Marcel Dekker. ; , s. 193-244
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Bokkapitel (refereegranskat)abstract
- Various aspects of alkyd emulsion technology have been investigated. Firstly, the influence of alkyd oil length, acid value and hydroxyl number, as well as the type of surfactant used as emulsifier, on shear stability of alkyds emulsions have been studied. It was found that the acid value was the most important alkyd parameter, the stability increasing with increasing oil length. It is also shown that anionic surfactants give emulsions with small droplet sizes down at lower concentrations than nonionics. Secondly, polymerizable nonionic surfactants have been tested as emulsifiers and compared with conventional surfactants of the same HLB. It was found that surfactants capable of participating in the autoxidative curing process give faster drying and improved film hardness compared with non-reactive surfactants. Thirdly, the distribution of driers between the alkyd phase and the water phase has been investigated. It was found that low pH and the use of hydrophilic anionic surfactants, such as SDS, favour partitioning of cobalt into the aqueous phase which is unfavourable with respect to drying properties.
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| 6. |
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| 7. |
- Bergström, L
(författare)
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Surface chemistry of silicon nitride powders: adsorption from non-aqueous solutions
- 1992
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Ingår i: Colloids and Surfaces. - 0166-6622 .- 1873-4340. ; 69, s. 53-64
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Tidskriftsartikel (refereegranskat)abstract
- The adsorption behaviour in cyclohexane of different silicon nitride powders have been studied. Adsorption isotherms of organic probe molecules covering a wide spectra of Lewis acidity/basicity showed large variation in adsorption behaviour between the different probes. Mathematical analysis showed that the adsorption data could be described by a Langmuir-Freundlich type of isotherm. Using a previously presented model of the silicon nitride surface, it was possible to relate the variation of isoelectric point in water between the three powders to a difference in the relative site density of silanol and amino groups on the surface. It was found that the maximum concentration (M) of benzoic acid increased linearly while M of pyridine decreased with an increase in the relative amount of amino groups on the surface.
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| 8. |
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| 9. |
- Bergström, L, et al.
(författare)
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The effect of wet and dry milling on the surface properties of silicon nitride powders
- 1991
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Ingår i: Ceramics Today. - : Elsevier. ; , s. 1005-1014
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Bokkapitel (refereegranskat)abstract
- The effects of dry milling in air and wet miling in isopropanol, on the surface properties of silicon nitride powders have been investigated. The ground powders have been analyzed with resoect to oxygen and carbon content, electrokinetic behviour, wetting characteristics and adsorption of acidic and basic probe molecules. The results show that dry milling in air leeds to a higher degree of surface oxidation which is correlated to substantially lower isoelectric points for dry milled vs. wet milled powders. The wet milled powders were contaminated by an adsorbed layer of isopropanol which resulted in an initially hydrophobic behaviour and low levels of adsorption of most probe molecules. This coating can be removed by heat treatment at elevated tempratures.
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| 10. |
- Bergström, S, et al.
(författare)
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Cloning and sequencing of human kappa-casein cDNA.
- 1992
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Ingår i: DNA Sequence. - 1042-5179 .- 1029-2365. ; 3:4, s. 245-6
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Tidskriftsartikel (refereegranskat)abstract
- A cDNA encoding kappa-casein of human milk was cloned and sequenced. The kappa-casein cDNA was isolated from a lambda gt11 library generated from mRNA prepared from a mammary gland biopsy obtained from a lactating woman. The library was screened with polyclonal rabbit antibodies raised against purified native kappa-casein. The obtained nucleotide sequence contained an ORF sufficient to encode the entire amino acid sequence of a kappa-casein precursor protein consisting of 182 amino acids. This includes a tentative signal peptide of 20 amino acids and a processed protein of 162 amino acids.
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| 11. |
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| 12. |
- Hansson, L, et al.
(författare)
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Expression of human milk beta-casein in Escherichia coli : comparison of recombinant protein with native isoforms.
- 1993
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Ingår i: Protein Expression and Purification. - : Elsevier BV. - 1046-5928 .- 1096-0279. ; 4:5, s. 373-81
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Tidskriftsartikel (refereegranskat)abstract
- Studies on physiological function and on structure-function relationships of human milk beta-casein have been limited. In this study, we have introduced the human beta-casein cDNA into vectors designed for expression in Escherichia coli. The inducible T7-based expression system resulted in high-level expression of recombinant beta-casein. The recombinant beta-casein, localized intracellularly in E. coli, was purified to homogeneity and compared with purified native beta-casein, in particular with respect to phosphorylation. The E. coli-produced beta-casein was found to comigrate with the full-length, nonphosphorylated native human beta-casein isoform on SDS-PAGE. An N-terminal peptide containing all tentative phosphorylation sites was isolated from the recombinant protein and analyzed by mass spectrometry. The molecular mass as well as the migration of this peptide on reversed-phase chromatography confirmed that it was unphosphorylated.
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| 13. |
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| 14. |
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| 15. |
- Jaenson, Thomas G. T., et al.
(författare)
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The ecology of lyme borreliosis in Sweden
- 1994. - 1
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Ingår i: Lyme borreliosis. - New York : Springer-Verlag New York. - 9781461524151 ; , s. 113-115
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The geographical distribution of Lyme borreliosis (Lb) in the North European countries appears to coincide with the geographical distribution of the principal vector, the common tick Ixodes ricinus. We have found that in Sweden this tick species occurs in the southern and south-central parts of the country and along the coast of northern Sweden. This area corresponds with the distributional area of Lyme borreliosis. I. ricinus, and thus also Borrelia burgdorferi s.l., are in general not present in the interior of North Sweden, presumably because the climate is too harsh for the vector.
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| 16. |
- Jonsson, Maria, et al.
(författare)
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Heterogeneity of outer membrane proteins in Borrelia burgdorferi : comparison of osp operons of three isolates of different geographic origins.
- 1992
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Ingår i: Infection and Immunity. - : American Society for Microbiology. - 0019-9567 .- 1098-5522. ; 60:5, s. 1845-53
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Tidskriftsartikel (refereegranskat)abstract
- Biochemical and immunochemical studies of the outer membrane proteins of Borrelia burgdorferi have shown that the OspA and OspB proteins from strains of different geographic origins may differ considerably in their reactivities with monoclonal antibodies and in their apparent molecular weights. To further characterize this variation in Osp proteins between strains, the osp operons and deduced translation products from two strains, one from Sweden (ACAI) and one from eastern Russia (Ip90), were studied. Polyacrylamide gel electrophoresis and Western blot (immunoblot) analyses confirmed differences between ACAI, Ip90, and the North American strain B31 in their Osp proteins. The sequences of the ospA and ospB genes of ACAI and Ip90 were compared with that of the previously studied osp operon of B31 (S. Bergström, V. G. Bundoc, and A. G. Barbour, Mol. Microbiol. 3:479-486, 1989). The osp genes of ACAI and Ip90, like the corresponding genes of B31, were found on plasmids with apparent sizes of about 50 kb and are cotranscribed as a single unit. Pairwise comparisons of the nucleotide sequences revealed that the ospA genes of ACAI and Ip90 were 85 and 86% identical, respectively, to the ospA gene of strain B31 and 86% identical to each other. The ospB sequences of these two strains were 79% identical to the ospB gene of B31 and 81% identical to each other. There was significantly greater similarity between the ospA genes of the three different strains than there was between the ospA and ospB genes within each strain. These studies suggest that the duplication of osp genes in B. burgdorferi occurred before the geographical dispersion of strains represented by ACAI, Ip90, and B31.
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| 17. |
- Lidén, E, et al.
(författare)
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Surface modification and dispersion of silicon nitride and silicon carbide powders
- 1991
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Ingår i: Journal of the European Ceramic Society. - 0955-2219 .- 1873-619X. ; 7, s. 361-368
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Tidskriftsartikel (refereegranskat)abstract
- A surface modification technique using controlled hydrolysis and polymerization of Al-alkoxide is oresented. It was found by measuring the electrokinetic behaviour and the adsorption properties that a minimum amount of about 0.5 mg Al/m2 was necessary to give SiC and Si3N4 in cyclohexane using a commercial dispersant with an acidic headgroup.
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| 18. |
- Lindmark, G, et al.
(författare)
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Prognostic predictors in colorectal cancer.
- 1994
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Ingår i: Diseases of the Colon & Rectum. - 0012-3706 .- 1530-0358. ; 37:12, s. 1219-27
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Better prognostic predictors in colorectal cancer than the Dukes stage are necessary for individualized therapy and follow-up.METHODS: Survival among 212 patients operated on for colorectal cancer was examined regarding various clinical, histopathologic, cellular, and serologic tumor characteristics.RESULTS: Beside the Dukes stage, which was the most powerful variable, the erythrocyte sedimentation rate, leukocyte blood count, alkaline phosphatase, aspartate aminotransferase, six different serum tumor markers, number of small blood vessels, and age were found to be significantly associated with survival. The leukocyte blood count, alkaline phosphatase, and aspartate aminotransferase retained their significance in a multivariate model including tumor differentiation, local tumor stage, and age. Inclusion of tissue polypeptide antigen, the most powerful tumor marker in the multivariate model, showed that only the tumor stage, tissue polypeptide antigen, and age were statistically significantly correlated to survival. This was valid both for the group of patients considered as potentially curable and for those who potentially have been cured (Dukes Stages A-C).CONCLUSIONS: A great number of prognostic predictors failed to discard Dukes stage as the best one. One serum tumor marker, tissue polypeptide antigen, contains independent additional prognostic information.
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