| 1. |
- Eriksson, Håkan
(författare)
-
Controlled release of preservatives using dealuminated zeolite Y
- 2008
-
Ingår i: Journal of Biochemical and Biophysical Methods. - : Elsevier BV. - 0165-022X .- 1872-857X. ; 70:6, s. 1139-1144
-
Tidskriftsartikel (refereegranskat)abstract
- This study demonstrates that dealuminated zeolite Y can act as a depot after adsorption of phenol derived preservatives. Upon suspension of zeolite loaded with the preservative m-cresol, equilibrium was quickly reached between free and adsorbed m-cresol. The equilibrium concentration of m-cresol was below 1 mM, however, it was enough to kill bacteria such as Escherichia coli and Staphylococcus aureus under metabolically active conditions. Killing of bacteria were not obtained under non-proliferating conditions and m-cresol was only released from the zeolite upon bacterial activity. Together, these results demonstrate an interesting potential use of dealuminated zeolite Y containing adsorbed preservatives for preventing microbial growth in numerous applications in industry and clinical setting.
|
|
| 2. |
- Hakkarainen, Minna
(författare)
-
Developments in multiple headspace extraction
- 2007
-
Ingår i: Journal of Biochemical and Biophysical Methods. - : Elsevier BV. - 0165-022X .- 1872-857X. ; 70:2, s. 229-233
-
Forskningsöversikt (refereegranskat)abstract
- This paper reviews new developments in multiple headspace extraction (MHE), especially its combination with two miniaturized extraction techniques, solid-phase microextraction (SPME) and single-drop microextraction (SDME). The combination of the techniques broadens the applicability of SPME and SDME to quantitative determination of analytes in complex liquid and solid matrixes. These new methods offer several advantages over traditional liquid-solid, liquid-liquid and headspace extraction techniques. The potential applications include extraction of volatiles and semivolatiles from environmental and physiological samples and from different polymer products such as medical and biomedical materials, food packaging and building materials. The theoretical principals of the techniques are also briefly reviewed.
|
|
| 3. |
- Hjerten, Maria, et al.
(författare)
-
Renewable enzyme reactors based on beds of artificial gel antibodies.
- 2008
-
Ingår i: Journal of Biochemical and Biophysical Methods. - : Elsevier BV. - 0165-022X .- 1872-857X. ; 70:6, s. 1188-1191
-
Tidskriftsartikel (refereegranskat)abstract
- A novel approach is described for the synthesis of beds for enzyme reactors. The method is based on the use of artificial antibodies in the form of polyacrylamide gel particles with diameters around 0.1-0.3 mm. These gel particles mimic protein antibodies, raised in experimental animals, in the sense that they selectively recognize and adsorb only the protein present during the preparation of the "antibodies". The gel antibodies have several advantages over conventional protein antibodies, which can be taken advantage of in the design of enzyme reactors; for instance, if upon prolonged use the immobilized enzyme loses its activity it can easily be replaced by an active enzyme, which is not possible when the enzyme is immobilized via a conventional protein antibody (a new bed with immobilized protein antibodies must be prepared); and equally or more remarkable: the enzyme can be applied in the form of a non-purified extract since the selectivity of the artificial gel antibodies is so high that they will "fish-out" the enzyme, but no other proteins in the extract. In addition, no preconcentration of the enzyme solution is required prior to the immobilization, since the enzyme is enriched at the top of the column upon the application. These unique properties make enzyme reactors based on artificial gel antibodies very attractive, also in process chromatography. The potential application range of the artificial gel antibodies is enormous since the same method for their synthesis can be used independent of the structure and the size of the "antigen"; for instance, renewable biosensors based on gel antibodies for the selective detection of protein biomarkers, as well as pathogenic viruses, bacteria, and spores (for instance Anthrax) should not be difficult to design.
|
|
| 4. |
- Kalbin, Georgi, et al.
(författare)
-
Effects of UV-B in biological and chemical systems : equipment for wavelength dependence determination
- 2005
-
Ingår i: Journal of Biochemical and Biophysical Methods. - : Elsevier BV. - 0165-022X .- 1872-857X. ; 65:1, s. 1-12
-
Tidskriftsartikel (refereegranskat)abstract
- The thinning of the stratospheric ozone layer has prompted a large number of studies of UV-B-induced effects in biological and chemical systems. The wavelength dependency of such effects is of interest from mechanistic, physiological or economic points of view. Here, we describe an apparatus for determining the wavelength dependency of UV-B effects in biological and chemical systems. The apparatus consists of a high intensity UV radiation source and narrow bandpass filters to produce UV radiation in even intervals (between 280 and 360 nm). The usefulness of the equipment is demonstrated in two different systems: 1) Chalcone synthase (CHS) gene is up-regulated by UV-B radiation. Therefore quantitative analysis of the CHS gene expression was chosen in the present investigation for studies of the wavelength dependency of gene expression regulation in plants. Maximum induction of CHS expression was found at 300 nm with a 12-fold induction compared with the control; 2) The wavelength dependency of formation of dioxin-like photoproducts from the brominated flame retardant decabrominated diphenyl ether (DeBDE) is described. This is an example of UV-B-induced conversion of non-toxic species into a number of products of which some may be toxic in the environment. In the UV interval studied, the highest dioxin-like activity was found in the sample irradiated at 330 nm and therefore this wavelength is most important for the mechanism involved in photoconversion of DeBDE.
|
|
| 5. |
- Lundqvist, Helen, et al.
(författare)
-
Evaluation of electron spin resonance for studies of superoxide anion production by human neutrophils interacting with Staphylococcus aureus and Staphylococcus epidermidis.
- 2008
-
Ingår i: Journal of Biochemical and Biophysical Methods. - : Elsevier BV. - 0165-022X .- 1872-857X. ; 70:6, s. 1059-1065
-
Tidskriftsartikel (refereegranskat)abstract
- The present study evaluates electron spin resonance (ESR) and the spin trapper 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline-N-oxide (DEPMPO) for analysis of superoxide radical production by human neutrophils interacting with viable Staphylococcus aureus and Staphylococcus epidermidis bacteria. To avoid auto-activation due to interaction with glass surfaces, neutrophils were preincubated in plastic tubes until the peak response was reached, and then transferred to a quartz flat cell to record the ESR spectra. The time point for peak response was identified by parallel analysis of the bacteria-neutrophil interaction using luminol amplified chemiluminescence. We found detectable ESR spectra from neutrophils interacting with as few as five bacteria of the weak activating S. epidermidis per neutrophil. Addition of the NADPH oxidase inhibitor diphenylene iodonium totally abolished spectra. Catalase, DMSO or an iron chelator had no impact on the produced spectra and ionomycin, a selective activator of intracellular NADPH oxidase, gave significant ESR spectra. Taken together, our results indicate that DEPMPO is cell permeable and detects NADPH oxidase derived superoxide anions formed in phagosomes or released by human neutrophils phagocytosing viable S. aureus and S. epidermidis. The technique may be used as a sensitive tool to evaluate superoxide anion production in human neutrophils.
|
|
| 6. |
- Ramser, Kerstin, et al.
(författare)
-
A combined micro-resonance Raman and absorption set-up enabling in vivo studies under varying physiological conditions : the nerve globin in the nerve cord of Aphrodite aculeata
- 2007
-
Ingår i: Journal of Biochemical and Biophysical Methods. - : Elsevier BV. - 0165-022X .- 1872-857X. ; 70:4, s. 627-633
-
Tidskriftsartikel (refereegranskat)abstract
- We hereby report on the design of a set-up combining micro-resonance Raman and absorption spectroscopy with a microfluidic system. The set-up enabled us to study the nerve globin of Aphrodite aculeata in the functional isolated nerve cord under varying physiological conditions for extended periods of time. The oxygenation cycle of the organism was triggered by utilizing the microfluidic system that allowed for a fast switch between aerobic and anaerobic conditions. The nerve globin was found to very easily shift from a penta-coordinated high spin ferrous form to the oxy state upon a change from anaerobic to aerobic conditions. The observed fast reaction to varying O2 concentrations supports an oxygen-carrying and/or -storing function of the nerve globin. In addition, by combining resonance Raman and absorption spectroscopy, the physiological response could be distinguished from light-induced effects.
|
|
| 7. |
- Rezeli, Melinda, et al.
(författare)
-
A new approach for on-line enrichment in electrophoresis of dilute protein solutions.
- 2008
-
Ingår i: Journal of Biochemical and Biophysical Methods. - : Elsevier BV. - 0165-022X .- 1872-857X. ; 70:6, s. 1098-1103
-
Tidskriftsartikel (refereegranskat)abstract
- A method is described for on-line enrichment/zone sharpening of a sample of negatively charged proteins (an analogous method for cationic proteins can be designed). The sample is applied on the top of a 5-mm thick layer of a neutral polyacrylamide gel which rests on another 5-mm thick, large-pore polyacrylamide gel which contains positively charged groups. The latter gel layer is attached to the neutral gel column, used for the electrophoretic separation of the proteins. When a voltage is applied the proteins start migrating and become electrostatically adsorbed at the top of the charged, large-pore gel layer (pH 5.4). With the upper electrode vessel filled with a buffer of a pH higher (pH 7.7) than that employed in the enrichment step and with a voltage between the electrodes, these enriched proteins are released (because the enrichment gel is non-charged at pH 7.7) with zone sharpening and migrate into the 5-cm long column (i.d. 5 mm) of a neutral, large-pore polyacrylamide gel for electrophoretic analysis. Upon the electrophoretic migration from the enrichment gel into the separation gel a second zone sharpening may occur, if the increase in pH from 5.4 to 7.7 in the separation gel is not close to momentary. By employing colored test proteins the efficiency of the enrichment step is visually illustrated by a picture. The principle of the concentration method described has been employed also in chromatographic experiments and can with appropriate modifications also be used in other electrophoretic methods, such as capillary electrophoresis.
|
|
| 8. |
- Råvik, Mattias, et al.
(författare)
-
A method for microbial cell surface fingerprinting based on surface plasmon resonance
- 2007
-
Ingår i: Journal of Biochemical and Biophysical Methods. - : Elsevier BV. - 0165-022X .- 1872-857X. ; 70:4, s. 595-604
-
Tidskriftsartikel (refereegranskat)abstract
- A method for microbial cell surface fingerprinting using surface plasmon resonance (SPR) is suggested. Four different Escherichia coli mutants have been used as model cells. Cell surface fingerprints were generated by registration of the interaction between the cell mutants and four different surfaces, with different physical and chemical properties, when a cell suspension was flown over the surface. Significant differences in fingerprint pattern between some of the mutants were observed. At the same time, the physical properties of the cell surfaces were determined using microelectrophoresis, contact angle measurements and aqueous two-phase partitioning and compared to the SPR fingerprints. The generated cell surface fingerprints and the physical property data were evaluated with multivariate data analysis that showed that the cells were separated into individual groups in a similar way using principal component analysis plots (PCA).
|
|
| 9. |
- Råvik, M, et al.
(författare)
-
A method for microbial cell surface fingerprinting based on surface plasmon resonance
- 2007
-
Ingår i: Journal of Biochemical and Biophysical Methods. - 0165-022X .- 1872-857X. ; 70:4, s. 595-604
-
Tidskriftsartikel (refereegranskat)abstract
- A method for cell surface fingerprinting using surface plasmon resonance (SPR) is suggested. Four different Esherichia coli mutants have been used as model cells, which were cultivated in shake flasks. Cell surface fingerprints were generated by registration of the interaction between the cell mutants and four different surfaces, with different physical and chemical properties, when a cell suspension was flown over the surface. Significant differences between some of the isolates were observed. Comparative measurements of physical property data are also included. A method for microbial cell surface fingerprinting using surface plasmon resonance (SPR) is suggested. Four different Escherichia coli mutants have been used as model cells. Cell surface fingerprints were generated by registration of the interaction between the cell mutants and four different surfaces, with different physical and chemical properties, when a cell suspension was flown over the surface. Significant differences in fingerprint pattern between some of the mutants were observed. At the same time, the physical properties of the cell surfaces were determined using microelectrophoresis, contact angle measurements and aqueous two-phase partitioning and compared to the SPR fingerprints. The generated cell surface fingerprints and the physical property data were evaluated with multivariate data analysis that showed that the cells were separated into individual groups in a similar way using principal component analysis plots (PCA)
|
|
| 10. |
- Bagdonaite, Kristina, et al.
(författare)
-
Analysis of 3-aminopropionamide: A potential precursor of acrylamide
- 2006
-
Ingår i: Journal of Biochemical and Biophysical Methods (Proceedings). - : Elsevier BV. - 0165-022X. ; 69:1-2, s. 215-221
-
Konferensbidrag (refereegranskat)abstract
- An analytical method for the analysis of 3-aminopropionamide (3-APA) based on derivatization with dansyl chloride and liquid chromatography/fluorescence detection was developed. We have analysed 3-APA formation in raw potatoes, grown and stored under different condition, green and roasted coffee beans and in freeze dried mixtures of asparagine with sucrose and glucose in molar ratio of 1:0.5, 1: 1, and 1: 1.5. In potatoes the 3-APA content varied depending on the potato variety. We detected 3-APA in potatoes up to 14 mu g/g fresh weight. In the model experiment glucose had a stronger capacity to form 3-APA. The substance was formed at temperatures as low as 130 degrees C. However, in the model experiment with sucrose 3-APA was formed not below 150 degrees C. In heated mixtures with increasing molar ratio of sucrose at 170 degrees C we noticed a decrease of 3-APA and in the same mixtures at 150 degrees C we observed an increase of 3-APA. In coffee 3-APA was not formed, neither in green nor in roasted beans. (c) 2006 Elsevier B.V. All tights reserved.
|
|
