| 1. |
- Carlsson, Annelie, et al.
(författare)
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Prevalence of IgA-antigliadin antibodies and IgA-antiendomysium antibodies related to celiac disease in children with Down syndrome
- 1998
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Ingår i: Pediatrics. - : American Academy of Pediatrics (AAP). - 1098-4275 .- 0031-4005. ; 101:2, s. 5-272
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: This study was undertaken to investigate the prevalence of celiac disease in children and adolescents with Down syndrome.MATERIAL AND METHODS: Forty-three children and adolescents with Down syndrome were screened for IgA-antigliadin antibodies (AGA) and IgA-antiendomysium antibodies (EMA). Patients found to be either AGA- or EMA-positive were investigated further with intestinal biopsy.RESULTS: None of the 43 patients had known celiac disease at entry into the study; 37% (16/43) were found to have AGA levels above normal, and 16% (7/43) to be EMA-positive. Of the 15 patients who underwent biopsy, 8 manifested villous atrophy. Villous atrophy was present in all 7 of the EMA-positive patients, whereas the villi were normal in 7 of the 13 AGA-positive patients who underwent biopsy.CONCLUSIONS: EMA is a good immunologic marker for use in screening for celiac disease, and screening is justified in patients with Down syndrome.
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| 2. |
- Andersson, M, et al.
(författare)
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Determination of the pore-size distribution in gels
- 1995
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Ingår i: Bioseparation. - 1573-8272. ; 5:2, s. 65-72
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Tidskriftsartikel (refereegranskat)abstract
- A method for determination of the accessible volume fraction in gels as function of the molecular weight of the solutes is presented. The pore-size distribution is determined by measuring the rate of diffusion of a mixture of solutes into a gel using gel filtration for separation. The solutes, of various sizes, are detected by refractive index measurements. Two marker molecules (blue dextran and glucose) were used to determine the gel void and the amount of liquid adhering to the surface. The technique is simple and can easily be adapted to other systems of a porous nature (membranes, catalyst pellets etc.). The method is applied to an N-isopropylacrylamide gel. This gel is sensitive to temperature changes. A considerable increase in volume is obtained when the temperature is decreased. This makes it suitable for use as a separation agent in gel extraction. In order to assess the performance of this unit operation the pore size distribution for the N-isopropylacrylamide gel was determined at 10 degrees C, 20 degrees C and 30 degrees C, using mixtures of different dextrans as well as different polyethylene glycols.
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| 3. |
- Andersson, M, et al.
(författare)
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Diffusion of glucose and insulin in a swelling N-isopropylacrylamide gel
- 1997
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Ingår i: International Journal of Pharmaceutics. - 1873-3476. ; 157:2, s. 199-208
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Tidskriftsartikel (refereegranskat)abstract
- The diffusional characteristics for poly(N-isopropylacrylamide) (NiPAAm) gel have been investigated. This gel is a critical gel which means that small changes in the environment influence the gel volume considerably. The effective diffusion coefficients for the solutes glucose and insulin were determined in batch experiments with the solutes diffusing out from small cylindrical gel bodies with diameters of 2.4-2.9 mm and at temperatures below the critical temperature: 10, 20 and 30 degrees C. The effective diffusion coefficients were obtained by fitting the experimental data to a mathematical model considering back-mixing and time delay in the experimental set-up, dilution due to the adsorbed liquid on the gel bodies and partition due to the exclusion effect. The effective diffusion coefficient for glucose increases from 2.7.10(-10) to 4.7.10(-10) m(2)/s when the temperature increases from 10 to 30 degrees C, following the Wilke-Chang relationship. This implies that the effect of the network is negligible compared with the effect of the temperature. However, for a solute with a molecular weight of about 6000 the network has a considerable effect. The effective diffusion coefficient for insulin increases from 4.4.10(-10) to 5.9.10(-10) m(2)/s when the temperature increases from 10 to 30 degrees C, which is less than expected from the Wilke-Chang relationship. This indicates an increased resistance for diffusion inside the gel due to shrinking. (C) 1997 Elsevier Science B.V.
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| 4. |
- Andersson, M, et al.
(författare)
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Swelling kinetics of poly(N-isopropylacrylamide) gel
- 1998
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Ingår i: Journal of Controlled Release. - 1873-4995. ; 50:1-3, s. 273-281
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Tidskriftsartikel (refereegranskat)abstract
- In many gel applications the swelling and shrinking kinetics are very important, e.g. in controlled/slow release, where the kinetics determine the rate of out-diffusion of the active component, and in gel extraction where the gel is swollen and shrunk several times. In this study swelling kinetics of poly(N-isopropylacrylamide) gel (NiPAAm gel) was determined by monitoring the swelling process using a stereo microscope and a video camera. The swelling of spherical gel bodies could conveniently be studied after a temperature change. The results obtained were treated according to the approach of Tanaka and Fillmore, in which the swelling and shrinking of a gel is described as a motion of the gel network according to the diffusion equation. This was shown to be valid when the temperature changes are kept below the critical point of the gel. However, the model fails to describe the shrinking process when passing from below to above the critical temperature. The collective diffusion coefficient (D), defined as the osmotic bulk modulus divided by the friction factor, was determined by fitting to the experimental data. D was found to increase with temperature according to the Wilke-Chang relation D=2.0.10(-11)+7.6.10(-17).T/mu. The results were used to simulate the swelling/shrinking process. The simulations show the importance of having sufficiently small gel bodies to achieve a short swelling time. (C) 1998 Elsevier Science B.V.
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| 5. |
- Axelsson, Helén, 1971, et al.
(författare)
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A New Methodology for Greenhouse Gas Reduction in Industry through Improved Heat Exchanging and/or Integration of Combined Heat and Power
- 1999
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Ingår i: Applied Thermal Engineering. ; 19/1999, Issue 7, s. 707-731
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a method that identi®es economically optimal combinations of enhanced heat recovery, integration of combined heat and power (CHP), and fuel switching, in an existing industrial energy system at various emission levels. Novel types of composite curves based on pinch technology, representing the existing temperature levels for supplying heat and the possible ones that may be attained after retro®tting, are used as tools for estimating the opportunities for CHP and the trade-off between improved heat exchangin
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| 6. |
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| 7. |
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| 8. |
- Carlsson, Annelie, et al.
(författare)
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Prevalence of IgA-antiendomysium and IgA-antigliadin autoantibodies at diagnosis of insulin-dependent diabetes mellitus in Swedish children and adolescents
- 1999
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Ingår i: Pediatrics. - : American Academy of Pediatrics (AAP). - 1098-4275 .- 0031-4005. ; 103:6 I, s. 1248-1252
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Tidskriftsartikel (refereegranskat)abstract
- Objective. This study was conducted to investigate the prevalence of celiac disease (CD) in children and adolescents at diagnosis of insulin- dependent diabetes mellitus (IDDM) before insulin treatment was started. Material and Methods. At diagnosis of IDDM, and before treatment was started, 115 children and adolescents were screened for IgA-antiendomysium (EMA) and IgA-antigliadin antibodies (AGA). Those found to be EMA-positive and/or AGA- positive were investigated further with intestinal biopsy. Results. Of the 115 patients, 2 had known CD at diagnosis of IDDM; of the remainder of patients, 6% (7/113) were found to be EMA-positive and 9% (10/113) were found to have AGA levels above normal. Of the 6 patients who underwent biopsy, 5 manifested villous atrophy. In addition, 2 patients with high EMA and AGA antibody titers refused biopsy, and 4 patients with low EMA and/or AGA titers were found to have normal titers at control before biopsy decision. Conclusion. Because the prevalence of CD at diagnosis of IDDM would seem to be 6% to 8%, screening for CD seems to be justified among patients with newly diagnosed IDDM.
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| 9. |
- Gustavsson, Per-Erik, et al.
(författare)
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Direct measurements of convective fluid velocities in superporous agarose beads
- 1998
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Ingår i: Journal of Chromatography A. - 0021-9673. ; 795:2, s. 199-210
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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.
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| 10. |
- Gustavsson, Per-Erik, et al.
(författare)
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Superporous agarose beads as a hydrophobic interaction chromatography support
- 1999
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Ingår i: Journal of Chromatography A. - 0021-9673. ; 830:2, s. 275-284
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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.
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