| 391. |
- Norberg, Katarina
(författare)
-
Intercultural education and teacher education in Sweden
- 2000
-
Ingår i: Teaching and Teacher Education. - : Elsevier. - 0742-051X .- 1879-2480. ; 16:4, s. 511-519
-
Tidskriftsartikel (refereegranskat)abstract
- The Swedish school is a meeting place for different cultures. Gender and class variations have been recognized for many years. More recently, ethnic, religious and linguistic diversity has also entered Swedish classrooms. This article examines these new educational circumstances in three parts. The first section defines some multicultural terms in Swedish context and briefly describes Sweden as a multicultural society. The second section discusses different pedagogical strategies in Swedish multicultural classrooms where cultural diversity problematizes traditional education. The final section addresses the need for an intercultural perspective in teacher education.
|
|
| 392. |
- Nordenhäll, C, et al.
(författare)
-
Airway inflammation following exposure to diesel exhaust : a study of time kinetics using induced sputum
- 2000
-
Ingår i: European Respiratory Journal. - : European Respiratory Society (ERS). - 0903-1936 .- 1399-3003. ; 15:6, s. 1046-1051
-
Tidskriftsartikel (refereegranskat)abstract
- The adverse health effects of particulate matter pollution are of increasing concern. In a recent bronchoscopic study in healthy volunteers, pronounced airway inflammation was detected following exposure to diesel exhaust (DE). The present study was conducted in order to evaluate the time kinetics of the inflammatory response following exposure to DE using induced sputum from healthy volunteers. Fifteen healthy nonsmoking volunteers were exposed to DE particles with a 50% cut-off aerodynamic diameter of 10 microm 300 microg x m(-3) and air for 1 h on two separate occasions. Sputum induction with hypertonic saline was performed 6 and 24 h after each exposure. Analyses of sputum differential cell counts and soluble protein concentrations were performed. Six hours after exposure to DE, a significant increase was found in the percentage of sputum neutrophils (37.7 versus 26.2% p=0.002) together with increases in the concentrations of interleukin-6 (12.0 versus 6.3 pg x mL(-1), p=0.006) and methylhistamine (0.11 versus 0.12 microg x L(-1), p=0.024). Irrespective of exposure, a significant increase was found in the percentage of sputum neutrophils at 24 as compared to 6 h, indicating that the procedure of sputum induction itself may change the composition of sputum. This study demonstrates that exposure to diesel exhaust induces inflammatory response in healthy human airways, represented by an early increase in interleukin-6 and methylhistamine concentration and the percentage of neutrophils. Induced sputum provides a safe tool for the investigation of the inflammatory effects of diesel exhaust, but care must be taken when interpreting results from repeated sputum inductions.
|
|
| 393. |
- Nordlund, Monica E, et al.
(författare)
-
Identification of the TRM2 gene encoding the tRNA(m5U54)methyltransferase of Saccharomyces cerevisiae.
- 2000
-
Ingår i: RNA. - 1355-8382 .- 1469-9001. ; 6:6, s. 844-60
-
Tidskriftsartikel (refereegranskat)abstract
- The presence of 5-methyluridine (m5U) at position 54 is a ubiquitous feature of most bacterial and eukaryotic elongator tRNAs. In this study, we have identified and characterized the TRM2 gene that encodes the tRNA(m5U54)methyltransferase, responsible for the formation of this modified nucleoside in Saccharomyces cerevisiae. Transfer RNA isolated from TRM2-disrupted yeast strains does not contain the m5U54 nucleoside. Moreover, a glutathione S-transferase (GST) tagged recombinant, Trm2p, expressed in Escherichia coli displayed tRNA(m5U54)methyltransferase activity using as substrate tRNA isolated from a trm2 mutant strain, but not tRNA isolated from a TRM2 wild-type strain. In contrast to what is found for the tRNA(m5U54)methyltransferase encoding gene trmA+ in E. coli, the TRM2 gene is not essential for cell viability and a deletion strain shows no obvious phenotype. Surprisingly, we found that the TRM2 gene was previously identified as the RNC1/NUD1 gene, believed to encode the yNucR endo-exonuclease. The expression and activity of the yNucR endo-exonuclease is dependent on the RAD52 gene, and does not respond to increased gene dosage of the RNC1/NUD1 gene. In contrast, we find that the expression of a trm2-LacZ fusion and the activity of the tRNA(m5U54)methyltransferase is not regulated by the RAD52 gene and does respond on increased gene dosage of the TRM2 (RNC1/NUD1) gene. Furthermore, there was no nuclease activity associated with a GST-Trm2 recombinant protein. The purified yNucR endo-exonuclease has been reported to have an NH2-D-E-K-N-L motif, which is not found in the Trm2p. Therefore, we suggest that the yNucR endo-exonuclease is encoded by a gene other than TRM2.
|
|
| 394. |
- Nordmark, Ulrika, et al.
(författare)
-
Conditions for Accurate Karl Fischer Coulometry Using Diaphragm-Free Cells
- 2000
-
Ingår i: Analytical Chemistry. - Washington, D. C., USA : American Chemical Society. - 0003-2700 .- 1520-6882. ; 72:1, s. 172-179
-
Tidskriftsartikel (refereegranskat)abstract
- Factors influencing the extent of formation of oxidizable reduction products in coulometric cells used for Karl Fischer (KF) determination of water were investigated. For methanolic KF reagents buffered with imidazole (Im) or diethanolamine (DEA) (separately or in combination), three parameters were found to be of outmost importance: the cathodic current density, the pH, and the concentration of protonated base (ImH+ or DEAH+). For reagents buffered with only Im, the relative formation of oxidizable reduction products varied in the range 2-40%; i.e., 51-70 g of water was found for a 50 g water sample, depending on the above-mentioned parameters. The lowest values were observed for reagents having a pH around 10 in combination with cathodic current densities in the range 2000-5000 mA cm-2. For all the Im-buffered reagents investigated, the addition of modifiers such as chloroform, hexanol, and carbon tetrachloride was found to decrease the formation of oxidizable reduction products significantly. For example, a reagent buffered at pH 10 containing 1 M hexanol gave less than 0.3% formation in the current density interval from 200 to 4000 mA cm-2. The best reagents based on the above-mentioned modifiers were tested in the continuous coulometric mode with errors typically in the interval 0-0.5% using optimum conditions. One prerequisite for obtaining such small errors with diaphragm-free continuous coulometry is to use a cathode area no larger than 0.002 cm2. For some of the reagents based on both Im and DEA, the formation of oxidizable reduction products was close to zero at certain current densities, although the analytical performance was not as good as for the reagents buffered solely by Im due to longer conditioning and titration times.
|
|
| 395. |
- Nordmark, Ulrika, et al.
(författare)
-
Optimum conditions for pulse generation in diaphragm-free Karl Fischer coulometry
- 2000
-
Ingår i: Fresenius' Journal of Analytical Chemistry. - : Springer. - 0937-0633 .- 1432-1130. ; 368:5, s. 456-460
-
Tidskriftsartikel (refereegranskat)abstract
- A flexible instrument was designed in order to investigate the influence of current magnitude, current duration and the frequency of the pulse generation on the error obtained in coulometric Karl Fischer titrations carried out in diaphragm-free cells. For a given current magnitude the lowest errors were obtained for current durations more than 60% of the total time for the pulse cycle. No significant influence of the pulse frequency (5-1000 Hz) was found independently of the pulse current duration for three different types of reagents intended fur diaphragm-free coulometry. For all reagents, the errors obtained with the home-built instrument were significantly smaller than those obtained with an optimized commercial titrator based on pulsed current generation. Using optimum conditions for the former instrument, in combination with an imidazole-buffered reagent at pH 10 containing chloroform as modifier, the accuracy was close to 100%. Thus, it is now possible to achieve the same high accuracy with diaphragm-free coulometry as with the conventional diaphragm based technique. The precision of the water determinations was affected by the size of the background.
|
|
| 396. |
- Nordmark, Ulrika, et al.
(författare)
-
Progress in pulsed-current Karl Fischer coulometry using diaphragm-free cells
- 2000
-
Ingår i: Fresenius' Journal of Analytical Chemistry. - : Springer. - 0937-0633 .- 1432-1130. ; 367:6, s. 519-524
-
Tidskriftsartikel (refereegranskat)abstract
- Factors influencing the accuracy of water determinations using diaphragm-free, pulsed current Karl Fischer (KF) coulometry were investigated with the new Metrohm 756 instrument. Results obtained with commercially available reagents from Riedel-deHaen and Merck were compared with home-made ones that were especially designed to minimize the formation of iodine-consuming reduction products generated in the cathode reaction. Positive errors in the range 2-5% were found for the commercial reagents as compared to 0.2-1% for the home-made ones which were buffered at about pH 10 containing modifiers like chloroform, hexanol or ethylene glycol. Except for the composition of the KF-reagent, the cathode current density and the titration rate were found to be critical parameters for the accuracy of the determinations. For all reagents investigated, the best results were obtained for the maximum generator current 400 mA (corresponding to a current density of 1400 mA cm(-2)) in combination with a maximum titration rate of 2000 mu g min(-1). Surprisingly, the errors found under optimum conditions for the pulse technique were always somewhat larger than the corresponding values obtained with continuous coulometry.
|
|
| 397. |
- Nordmark, Ulrika
(författare)
-
Quantitative determination of resin mixtures in coating colours for paper by multivariate analysis of data from pyrolysis-gas chromatography
- 2000
-
Ingår i: Journal of Analytical and Applied Pyrolysis. - : Elsevier. ; 55:1, s. 93-103
-
Tidskriftsartikel (refereegranskat)abstract
- Pulp and paper industries are interested in a technique for analysing the purchased resins used in coating colours. The concept of pyrolysis-gas chromatography in combination with chemometrics, i.e. principal component analysis and principal least squares, was used to develop improved methods for the quantitative analysis of tertiary mixtures based on latex resins. A principal least square model was made based on pyrolysis-gas chromatography data and a mass spectrometer was used to identify pyrolysis fragments. It was shown that the model accurately predicted the concentration of a resin in a tertiary mixture. The average error of prediction, for resin mixtures not previously shown for the model, was less than 4% by weight for each of the investigated resins.
|
|
| 398. |
- Nordström, Marie, et al.
(författare)
-
Concentrations of Organochlorines Related to Titers to Epstein-Barr Virus Early Antigen IgG as Risk Factors for Hairy Cell Leukemia
- 2000
-
Ingår i: Environmental Health Perspectives. ; 108:5, s. 441-5
-
Tidskriftsartikel (refereegranskat)abstract
- Hairy cell leukemia (HCL) is a rare chronic B-cell malignancy that, according to modern classifications, is a subgroup of non-Hodgkin lymphomas (NHLs) . A rapid increase in incidence of NHL has been reported in many countries. The reasons for this increase are largely unknown, but exposure to organochlorines has been suggested as a risk factor. Epstein-Barr virus is a human herpesvirus that has been associated with certain subgroups of NHL. In this study, we measured lipid adjusted blood concentrations (in nanogram per gram) of 36 congeners of polychlorinated biphenyls (PCBs) , p,p´-dichlorodiphenyldichloroethylene (p,p´-DDE) , hexachlorobenzene (HCB) , and four subgroups of chlordanes (trans-nonachlor, cis-nonachlor, MC6, and oxychlordane) in incident cases of HCL and controls from the general population. We obtained results on organochlorines and antibodies for 54 cases and 54 controls. Titers of antibodies to the Epstein-Barr early antigen and Epstein-Barr nuclear antigen, measured as P107, were correlated to concentrations of organochlorines to evaluate the possibility of an interaction between these factors in the pathogenesis of HCL. We found no significant difference in lipid-adjusted blood concentrations of total PCBs, p,p´-DDE, HCB, or the sum of the chlordanes between cases and controls. Titers of antibodies to Epstein-Barr early antigen IgG 40 were correlated to an increased risk for HCL. This risk was further increased in those with a level above the median value of p,p´-DDE, HCB, or the sum of the chlordanes, suggesting an interaction between Epstein-Barr virus and a higher concentration of these chemicals. We also found increased risk for the sum of immunotoxic PCB group.
|
|
| 399. |
|
|
| 400. |
- Novak, R, et al.
(författare)
-
Extracellular targeting of choline-binding proteins in Streptococcus pneumoniae by a zinc metalloprotease.
- 2000
-
Ingår i: Molecular Microbiology. - 0950-382X .- 1365-2958. ; 36:2, s. 366-376
-
Tidskriftsartikel (refereegranskat)abstract
- A genetic-based search for surface proteins of Streptococcus pneumoniae involved in adhesion identified a putative zinc metalloprotease (ZmpB). ZmpB shared high amino acid sequence similarities with IgA1 proteases of Gram-positive bacteria, but ZmpB had neither IgA1 nor IgA2 protease activity. Analysis of a family of surface-expressed proteins, the choline-binding proteins (Cbp's), in a zmpB-deficient mutant demonstrated a global loss of surface expression of CbpA, CbpE, CbpF and CbpJ. CbpA was detected within the cytoplasm. The zmpB-deficient mutant also failed to lyse with penicillin, a sign of lack of function of the Cbp LytA. Immunodetection studies revealed that the autolysin (LytA), normally located on the cell wall, was trapped in the cytoplasm colocalized with DNA and the transformation protein CinA. Trafficking of CinA and RecA to the cell membrane during genetic competence was also not observed in the zmpB-deficient mutant. These results suggest a protease dependent regulatory mechanism governing the translocation of CinA and the Cbp's LytA and CbpA of S. pneumoniae.
|
|
