Biomedical subjects

H Haario

Publications and source records attributed to H Haario.

6 recordsLinked to original sources

PubMed2000

Effect of inoculation of a TOL plasmid containing mycorrhizosphere bacterium on development of Scots pine seedlings, their mycorrhizosphere and the microbial flora in m-toluate-amended soil.

The purpose of this study was to evaluate the influence of introduced bacteria containing a contaminant degrading plasmid on the growth and survival of pine seedlings and mycorrhizosphere microbial flora in contaminated soil. The Pseudomonas fluorescens strain OS81, originally isolated from fungal hyphae in contaminated soil, was supplied with the TOL plasmid pWW0::Km (to generate OS81(pWW0::Km)) and inoculated in humus-soil microcosms with and without pine seedlings mycorrhized with Suillus bovinus. After 3 months of regular treatment with m-toluate (mTA) solutions, the introduced catabolic plasmid was found to be disseminated in the indigenous bacterial population of both mycorrhizosphere and soil uncolonized by the fungus. Transconjugants were represented by bacteria of the genera Pseudomonas and Burkholderia and their number correlated positively with the concentration of mTA applied. Indigenous mTA degrading bacteria with low similarity to Burkholderia species were also enriched in microcosms. They were mostly associated with mycorrhizal soil or fungal structures and virtually absent in microcosms without pines. The total number of Tol(+) bacteria was higher in mycorrhizospheric soil compared with bulk soil. Inoculation with P. fluorescens OS81(pWW0::Km) had a positive effect on the development of roots and fungus in contaminated soil. Both inoculation with the P. fluorescens OS81(pWW0::Km) and mTA contamination as well as the presence of mycorrhized pine roots and fungal hyphae had an effect on the microbial community structure of soil as measured by carbon source oxidation patterns. However, the impact of mTA on the microbial community was more prominent. The study indicates that an effect on plant and fungal development can be obtained by manipulating the mycorrhizosphere. Both introduction of the bacterium carrying the degradative plasmid and the plasmid itself are likely to have a positive effect not only on the organisms involved, but also on bioremediation of contaminated soil, a factor that was not directly monitored here.

Journal Article↗

PubMed2000

Improved detection of Listeria monocytogenes in soft mould-ripened cheese.

In comparison with standard methods, enrichment in half-Fraser broth for 24 h at 30 degrees C, followed by plating out onto Listeria monocytogenes blood agar (LMBA) and PALCAM medium combined with an additional streak proved to be the most rapid and specific method for the detection of indigenous L. monocytogenes populations from soft mould-ripened cheese. This procedure, with a high sensitivity (93%) and a low detection limit (1-10 cfu 25 g-1), provided negative and presumptive positive results within 2-3 d. Differences between LMBA, PALCAM and Oxford medium turned out to be highly significant (at 99% significance level); plating on LMBA after standard enrichment protocols giving the best overall results. An improvement in detection was also obtained by modifying the confirmation procedure. A loopful of culture (an additional streak) from PALCAM or Oxford medium was streaked on non-selective medium in addition to streaking only separate colonies as specified in the standards.

Cheese↗

PubMed1999

A new method with general diagnostic utility for the calculation of immunoglobulin G avidity.

The reference method for immunoglobulin G (IgG) avidity determination includes reagent-consuming serum titration. Aiming at better IgG avidity diagnostics, we applied a logistic model for the reproduction of antibody titration curves. This method was tested with well-characterized serum panels for cytomegalovirus, Epstein-Barr virus, rubella virus, parvovirus B19, and Toxoplasma gondii. This approach for IgG avidity calculation is generally applicable and attains the diagnostic performance of the reference method while being less laborious and twice as cost-effective.

Antibodies, Protozoan↗

PubMed1998

Optimization of selectivity in high-performance liquid chromatography using desirability functions and mixture designs according to PRISMA.

A computer program for the mobile phase optimization of high-performance liquid chromatography (HPLC) is described. The desirability function technique combined to the prisma mixture design was employed to enhance the quality of HPLC separations. The use of statistical models to predict the behaviour of retention times (tR) and band broadening at the different eluent compositions obtained by prisma was examined for dansyl amides and coumarins. The study showed that the dependence between the eluent composition and tR values of dansyl amides and coumarins can be expressed using quadratic regression models with a high degree of accuracy. Band broadening given by means of the band width at half-height (wh) was described by a linear regression model. Both models were used in calculating and predicting the resolution (Rs) in various solvent combinations. The desirability function converted the calculated (Rs) value into the desirability value (D), and the overall optimum was then defined by means of the overall desirability. The optimal eluent mixtures for the separation of compounds were easily read from the contour plot inside the horizontal plane of the prisma model. A good separation was achieved using the optimized solvent combination. Depending on the aims of the optimal separation, the program allows either optimization of critical pairs or achieving the overall optimum giving a reasonable separation for as many compounds as possible.

Chromatography, High Pressure Liquid↗

PubMed1996

Optimization of selectivity and resolution in micellar electrokinetic capillary chromatography with a mixed micellar system of sodium dodecyl sulfate and sodium cholate.

Selectivity and resolution were studied for the separation of seven corticosteroids by micellar electrokinetic capillary chromatography (MEKC) using a mixed micellar solution of sodium dodecyl sulfate (SDS) and sodium cholate (SC), buffered with 3-(N-morpholino)propanesulfonic acid (MOPS) or 3-[(1,1-dimethyl-2-hydroxyethyl)amino]-2-hydroxypropane sulfonic acid (AMPSO). The changes in selectivity were compared for the AMPSO-SDS-SC system by varying the pH and the concentrations of AMPSO, SDS and SC. The experimental design started with the central composite design and continued in a sequential manner. The optimum selectivity for the separation of the corticosteroids was calculated from the analyte migration times and the analyte velocities, by using empirical quadratic regression models. Satisfactory regression fits and coefficients of determination for prediction were obtained with cross-validated models. To optimize the resolution, the physical parameters of capillary length and analysis time were varied under the conditions optimal for the selectivity. In both the selectivity and the resolution, optimization the overall optimum was determined by using the desirability function technique. Analysis times were controlled by using 1,3-diaminopropane to influence the electroosmotic flow velocity (veo). The voltage was kept constant, which resulted in higher electric field strength in shorter capillaries. No changes in the selectivity were observed when 1,3-diaminopropane was used to control the electroosmotic flow velocity. Such an optimization technique, where the chemical and physical factors affecting the separation are treated independently, seemed to be effective for finding the best possible resolution for the corticosteroids.

Adrenal Cortex Hormones↗

PubMed1994

Optimized separation of seven corticosteroids by micellar electrokinetic chromatography.

The corticosteroids studied can be effectively separated by employing micellar electrokinetic capillary chromatography (MECC). The effect of pH, borate concentration and the sodium dodecyl sulfate (SDS) concentration on both the resolution and the selectivity was studied under 15 different experimental conditions. The experimental design was similar to the central composite design approach. Empirical quadratic regression models were derived for analyte migration time, band broadening and analyte velocity. Satisfactory regression fits and coefficients of determination for prediction were obtained with cross-validated models. The models for analyte migration time and analyte velocity were in good agreement with theory. Modeling of the band broadening seemed to be somewhat more complicated. Optimum conditions for resolution and selectivity were different. This is due to the fact that selectivity studies ignore the electroosmotic and band broadening properties of different electrolyte solutions. However, the study of the selectivity yielded good information about the suitability of the electrolyte systems for the particular separation problem. Although a high solubilizing power of SDS caused the corticosteroids to partition strongly into the SDS micelles, a good separation could be achieved at low SDS concentrations.

Adrenal Cortex Hormones↗