| 1. |
- Gustavsson, Per-Erik, et al.
(författare)
-
Direct measurements of convective fluid velocities in superporous agarose beads
- 1998
-
Ingår i: Journal of Chromatography A. - 0021-9673. ; 795:2, s. 199-210
-
Tidskriftsartikel (refereegranskat)abstract
- Superporous agarose beads contain two sets of pores, diffusion pores and so-called superpores or flow pores, in which the chromatographic flow can transport substances to the interior of each individual bead [Gustavsson and Larsson, J. Chromatogr. A 734 (1996) 231]. The existence of pore flow may be proven indirectly by the chromatographic performance of beads but it has never been directly demonstrated in a chromatographic bed. In this report, pore flow was directly measured by following the movement of micro-particles (dyed yeast cells) in a packed bed. The passage of the micro-particles through the superpores and through the interstitial pores was followed by a microscope/video camera focused on beads which were situated four layers from the glass wall. The video recordings were subsequently used to determine the convective fluid velocities in both the superpores and the interstitial pores. Experiments were carried out with three different bead size ranges, all of which contained superporous beads having an average superpore diameter of 30 mu m. The superpore fluid velocity as % of interstitial fluid velocity was determined to be 2-5% for columns packed with 300-500-mu m beads (3% average value), 6-12% for columns packed with 180-300 mu m beads (7% average value) and 11-24% for columns packed with 106-180-mu m beads (17% average value). These data were compared to and found to agree with theoretically calculated values based on the Kozeny-Carman equation. In order to observe and accurately measure fluid velocities within a chromatographic bed, special techniques were adopted. Also, precautions were made to ensure that the experimental conditions used were representative of normal chromatography runs. (C) 1998 Elsevier Science B.V.
|
|
| 2. |
- Gustavsson, Per-Erik, et al.
(författare)
-
Superporous agarose beads as a hydrophobic interaction chromatography support
- 1999
-
Ingår i: Journal of Chromatography A. - 0021-9673. ; 830:2, s. 275-284
-
Tidskriftsartikel (refereegranskat)abstract
- Superporous agarose beads were used as a support for hydrophobic interaction chromatography. These beads have large connecting flow pores in addition to their normal diffusion pores. The flow pores, which are approximately one fifth of the overall diameter of the superporous agarose beads, were earlier shown to give the beads improved mass transfer properties relative to homogeneous agarose beads (Gustavsson and Larsson, J. Chromatogr. A, 734 (1996) 231-240). Superporous agarose beads and homogeneous agarose beads of the same particle size range (106-180 mu m) were derivatized with phenyl groups. The properties of the superporous beads were then compared with the homogeneous beads in the separation of a mixture of three model proteins (ribonuclease A, lysozyme and bovine serum albumin) at various superficial flow velocities from 30 to 600 cm/h. The superporous beads gave satisfactory separation at flow velocities five times higher than was possible for homogeneous beads. The performance of the two types of beads was also compared in the purification of lactate dehydrogenase from a beef heart extract at a superficial flow velocity of 150 cm/h. The superporous beads performed considerably better, leading to twice the purification factor and twice the concentration of the desired product. The results were interpreted using the theoretical treatment given by Carta and Rodrigues (Carta and Rodrigues, Chem. Eng. Sci., 48 (1993) 3927). (C) 1999 Elsevier Science B.V. All rights reserved.
|
|
| 3. |
- Larsson, Anders, et al.
(författare)
-
Peroxidase labelling of chicken anti-bodies
- 1999
-
Ingår i: Food and Agricultural Immunology. - : Informa UK Limited. - 0954-0105 .- 1465-3443. ; 11:1, s. 43-49
-
Tidskriftsartikel (refereegranskat)abstract
- Chicken antibodies have several advantages over mammalian antibodies due to the phylogenetical differences between birds and mammals, resulting in an increased sensitivity and a decreased background in many immunological assays. So far, there has been a very limited use of avian antibodies. This is probably partly due to tradition but also because there are very few optimized methods for the labelling of chicken antibodies. We report upon the suitable conditions for peroxidase-labelling of chicken antibodies with a modified periodate method.
|
|
| 4. |
|
|
| 5. |
- Larsson, Per-Olof, et al.
(författare)
-
Direct measurement of intraparticle fluid velocity in superporous agarose beads
- 1998
-
Ingår i: Journal of Molecular Recognition. - 1099-1352. ; 11:1-6, s. 270-272
-
Tidskriftsartikel (refereegranskat)abstract
- Superporous agarose beads contain both normal diffusion pores and special, very wide superpores through which part of the chromatographic flow is transported, a situation that may greatly improve the chromatographic performance. For the first time such pore flow was measured directly by following the movement of microparticles (dyed yeast cells) through superporous beads packed in a chromatographic bed. The passage of the microparticles through the superpores and through the interstitial pores was recorded by a microscope/video camera, The video recordings were subsequently used to determine flow paths as well as the convective fluid velocities in both the superpores and the interstitial pores. The superpore fluid velocity was found to be proportional to the ratio between the squares of the respective pore diameters, which is in agreement with the Kozeny-Carman equation, Values for two-dimensional and three-dimensional tortuosity of the flow paths were measured and calculated respectively. (C) 1998 John Wiley & Sons, Ltd.
|
|
| 6. |
|
|
| 7. |
- Odin, Elisabeth, 1955, et al.
(författare)
-
Rapid method for relative gene expression determination in human tissues using automated capillary gel electrophoresis and multicolor detection
- 1999
-
Ingår i: J Chromatogr B Biomed Sci Appl. - 1387-2273. ; 734:1, s. 47-53
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to evaluate a direct and automated post-polymerase chain reaction (PCR) detection system to simultaneously determine the relative gene expression levels of nine cancer-related human genes. Total RNA was prepared from flash-frozen biopsies derived from human colorectal tumors or normal mucosa and reverse-transcribed to cDNA which was PCR-amplified using primer pairs corresponding to the studied genes. In each reaction, the forward primer was labeled with a fluorescent dye. The PCR products were pooled and an internal size standard with a uniquely colored fluorescent dye was added. The samples were then subjected to automated capillary gel electrophoresis. Fragment analysis software was used to calculate the relative gene expression using beta-actin as the reference gene. We found that automated capillary gel electrophoresis with multicolor detection is a rapid, accurate and highly reproducible method for separation and quantification of PCR-amplified cDNA.
|
|
| 8. |
|
|
| 9. |
- Berglund, Olof, et al.
(författare)
-
Factors influencing organochlorine uptake in age-0 brown trout (Salmo trutta) in lotic environments
- 1997
-
Ingår i: Canadian Journal of Fisheries and Aquatic Sciences. - 1205-7533. ; 54:12, s. 2767-2774
-
Tidskriftsartikel (refereegranskat)abstract
- In 1994 and 1995, we investigated the relationship between stream morphology and water chemistry and levels of organochlorines (HCB, PCB, and DDT) in young-of-the-year brown trout (Salmo trutta) from 25 streams in southern Sweden. Contrary to earlier findings for lakes, we found a positive relationship between trophic status (total phosphorus) and uptake of persistent pollutants in stream biota (trout). This difference between benthic, stream environments and pelagic, lake environments may be related to processes affecting pollutant uptake, i.e., pollutant "spiralling" or the shift from heterotrophy to autotrophy in streams. Land use in the catchment area of the streams also affected pollutant levels in trout, with higher levels in agricultural landscapes and lower levels in forested areas. Size of catchment area, however, did not influence uptake of pollutants in trout. The results indicate that eutrophication of streams by agricultural activities and excessive nutrient loading may increase uptake of persistent pollutants in stream biota.
|
|
| 10. |
- Carling, Tobias, et al.
(författare)
-
Hyperparathyroidism of multiple endocrine neoplasia type 1 : candidate gene and parathyroid calcium sensing protein expression
- 1995
-
Ingår i: Surgery. - 0039-6060 .- 1532-7361. ; 118:6, s. 924-931
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND:Hyperparathyroidism affects most patients with multiple endocrine neoplasia type 1 (MEN 1). This study investigates expression of the candidate MEN1 gene phospholipase C beta 3 (PLC beta 3) and expression and function of a putative calcium sensing protein (CAS) in hyperparathyroidism of MEN 1.METHODS:In 31 parathyroid glands from 17 patients with MEN 1, CAS distribution was studied immunohistochemically and parallel sections were explored for PLC beta 3 mRNA expression by in situ hybridization. Enzymatically dispersed parathyroid cells were analyzed for cytoplasmic calcium concentrations [Ca2+]i and parathyroid hormone (PTH) release.RESULTS:All glands exhibited a heterogeneously reduced CAS immunoreactivity, especially meager in nodularly assembled parathyroid cells. Calcium regulated [Ca2+]i and PTH release tended to be more deranged in the glands possessing the lowest immunostaining. Parathyroid PLC beta 3 invariably was homogeneously expressed, and this included even MEN 1 patients with reduced PLC beta 3 expression in endocrine pancreatic tumors.CONCLUSIONS:The findings support variable calcium insensitivity of [Ca2+]i and PTH release in hyperparathyroidism of MEN 1, apparently coupled to heterogeneously reduced CAS expression. For clarification of the role of PLC beta 3 in MEN 1 parathyroid tumorigenesis further study of this protein is required.
|
|
