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- Aspholm-Hurtig, Marina, et al.
(författare)
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Functional adaptation of BabA, the H. pylori ABO blood group antigen binding adhesin.
- 2004
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Ingår i: Science (New York, N.Y.). - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 305:5683, s. 519-22
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Tidskriftsartikel (refereegranskat)abstract
- Adherence by Helicobacter pylori increases the risk of gastric disease. Here, we report that more than 95% of strains that bind fucosylated blood group antigen bind A, B, and O antigens (generalists), whereas 60% of adherent South American Amerindian strains bind blood group O antigens best (specialists). This specialization coincides with the unique predominance of blood group O in these Amerindians. Strains differed about 1500-fold in binding affinities, and diversifying selection was evident in babA sequences. We propose that cycles of selection for increased and decreased bacterial adherence contribute to babA diversity and that these cycles have led to gradual replacement of generalist binding by specialist binding in blood group O-dominant human populations.
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| 2. |
- Gullberg, Jonas, et al.
(författare)
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Design of experiments : an efficient strategy to identify factors influencing extraction and derivatization of Arabidopsis thaliana samples in metabolomic studies with gas chromatography/mass spectrometry
- 2004
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Ingår i: Analytical Biochemistry. - : Elsevier BV. - 0003-2697 .- 1096-0309. ; 331:2, s. 283-295
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Tidskriftsartikel (refereegranskat)abstract
- The usual aim in metabolomic studies is to quantify the entire metabolome of each of a series of biological samples. To do this for complex biological matrices, e.g., plant tissues, efficient and reproducible extraction protocols must be developed. However, derivatization protocols must also be developed if GC/MS (one of the mostly widely used analytical methods for metabolomics) is involved. The aim of this study was to investigate how different chemical and physical factors (extraction solvent, derivatization reagents, and temperature) affect the extraction and derivatization of the metabolome from leaves of the plant Arabidopsis thaliana. Using design of experiment procedures, variation was systematically introduced, and the effects of this variation were analyzed using regression models. The results show that this approach allows a reliable protocol for metabolomic analysis of Arabidopsis to be determined with a relatively limited number of experiments. Following two different investigations an extraction and derivatization protocol was chosen. Further, the reproducibility of the analysis of 66 endogenous compounds was investigated, and it was shown that both hydrophilic and lipophilic compounds were detected with high reproducibility.
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| 3. |
- Jonsson, Pär, et al.
(författare)
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A strategy for identifying differences in large series of metabolomic samples analyzed by GC/MS
- 2004
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Ingår i: Analytical Chemistry. - Columbus, OH : American Chemical Society. - 0003-2700 .- 1520-6882. ; 76:6, s. 1738-1745
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Tidskriftsartikel (refereegranskat)abstract
- In metabolomics, the purpose is to identify and quantify all the metabolites in a biological system. Combined gas chromatography and mass spectrometry (GC/MS) is one of the most commonly used techniques in metabolomics together with 1H NMR, and it has been shown that more than 300 compounds can be distinguished with GC/MS after deconvolution of overlapping peaks. To avoid having to deconvolute all analyzed samples prior to multivariate analysis of the data, we have developed a strategy for rapid comparison of nonprocessed MS data files. The method includes baseline correction, alignment, time window determinations, alternating regression, PLS-DA, and identification of retention time windows in the chromatograms that explain the differences between the samples. Use of alternating regression also gives interpretable loadings, which retain the information provided by m/z values that vary between the samples in each retention time window. The method has been applied to plant extracts derived from leaves of different developmental stages and plants subjected to small changes in day length. The data show that the new method can detect differences between the samples and that it gives results comparable to those obtained when deconvolution is applied prior to the multivariate analysis. We suggest that this method can be used for rapid comparison of large sets of GC/MS data, thereby applying time-consuming deconvolution only to parts of the chromatograms that contribute to explain the differences between the samples.
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| 7. |
- Stener-Victorin, Elisabet, 1964, et al.
(författare)
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Perceptual matching for assessment of itch; reliability and responsiveness analyzed by a rank-invariant statistical method.
- 2003
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Ingår i: The Journal of investigative dermatology. - : Elsevier BV. - 0022-202X. ; 121:6, s. 1301-5
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to evaluate the reliability and responsiveness of a new device-perceptual matching by Matcher (Cefar Medical AB, Lund, Sweden)-in the assessment of the progress of experimentally induced itch as well as determine the reliability of the method in patients with skin disease and itch. The perceptual matching unit electrically stimulates the skin of the fingers in the left hand. When the amplitude of the sensation corresponded to that of the experienced itch, the subject was instructed to halt the stimulation and a value was automatically saved in the electronic device. A total of 36 healthy subjects and nine patients participated in the study. The healthy subjects were asked to rate the level of itch every 30 s during the first 5 min and thereafter every minute. The reliability was determined in a test-retest procedure of the time points 5, 10, and 15 min after induction of itching. To test the stability of the method, the first sensation of pain in healthy subjects without itch was determined every 10th minute during 60 min. In patients, the test-retest procedure was repeated within 5 min. Perceptual matching was found to be a reliable method of itch assessment, with no evidence for random individual disagreement between the assessments. The augmented rank order coefficient ra was excellent: 1.00 at 5 min; 0.99 at 10 min; and 1.00 at 15 min. There was a clear indication of responsiveness for detecting changes in itch over time, p
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| 8. |
- Svensson, Anna, et al.
(författare)
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Phases and structures of a polyion-surfactant ion complex salt in aqueous mixtures: cationic hydroxyethyl cellulose with dodecylsulfate counterions
- 2003
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Ingår i: Colloids and Surfaces A: Physicochemical and Engineering Aspects. - 0927-7757. ; 228:1-3, s. 91-106
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Tidskriftsartikel (refereegranskat)abstract
- A polyion-surfactant ion complex salt, cat-HECDS, has been synthesised, consisting of cationic hydroxyethyl cellulose w th dodecylsulfate counterions. Ternary phase diagrams have been established for aqueous mixtures of cat-HECDS with either the conventional surfactant NaDS or the polyelectrolyte cat-HECCl. Such mixtures represent the simplest possible aqueous mixtures of oppositely charged polymer and surfactant where the proportions of polyion and surfactant ion may be varied. Phases and structures were investigated by visual inspection through crossed polarisers and by small-angle X-ray scattering (SAXS),The pure complex salt cat-HECDS was insoluble in water, but it could absorb up to 60 wt.% water. No crystalline order was detected at any water content. Dissolution of the complex salt in water occurred if sufficient amounts of either surfactant or polyelectrolyte was added. A smaller excess of surfactant (50% by charge) than polyelectrolyte (100% by charge) was needed to dissolve the complex salt in the dilute region. The efficiency of excess NaDS to dissolve the complex salt was attributed to hydrophobic interactions be ween the surfactant and the cat-HEC backbone. The free surfactant concentration at the onset of dissolution was in good agreement with the critical association concentration observed in previous gel experiments.The investigated phase diagrams were dominated by a large isotropic phase containing micellar surfactant aggregates without long-range order. The micellar aggregation number varied from similar to20 for aqueous cat-HECDS to similar to80 for mixtures rich in NaDS. A small fraction of added complex salt was enough to destroy the hexagonal phase formed in binary mixtures of NaDS and water. The absence of liquid crystalline phases containing significant amounts of complex salt was attributed to the stiff character of the polyion and its low charge density. In a ternary complex salt-surfactant-water system studied previously, where the complex salt contained a flexible polyion with a high charge density, liquid crystalline phases were found at all proportions of complex salt. (C) 2003 Elsevier B.V. All ri hts reserved.
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| 9. |
- Xu, Hong-Tao, et al.
(författare)
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Effects of fucosylated milk of goat and mouse on Helicobacter pylori binding to Lewis b antigen
- 2004
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Ingår i: World Journal of Gastroenterology. - Beijing : WJG Press. - 1007-9327 .- 2219-2840. ; 10:14, s. 2063-2066
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Tidskriftsartikel (refereegranskat)abstract
- Aim:To evaluate the effects of animal milk containing fucosylated antigens on Helicobacter pylori (H pylon) binding to Lewis b antigen. Methods:A mammary gland expression vector containing human α1-3/4-fucosyltransferase cDNA sequences was constructed. Transient expression of human(α1-3/4-fucosyltransferase cDNA in goat mammary cell and establishment of transgenic mice were performed. The adhesion inhibitory properties of milk samples were analyzed by using Hpylori. Results: Goat milk samples were found to inhibit bacterial binding to Lewis b antigen. The highest inhibition was observed 42 h after injection of the plasmid. The binding activity of Hpylori to Lewis b antigen reduced mostly, by 83%, however milk samples from transgenic mice did not inhibit Hpylori binding to Lewis b antigen. Conclusion: The use of “humanized“ animal milk produced by the transgenic introduction of fucosylated antigen can perhaps provide an alternative therapy and preventive measure for Hpylori infection.
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