| 1. |
- Agardh, Daniel, et al.
(author)
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HLA-DQB1*0201/0302 is associated with severe retinopathy in patients with IDDM
- 1996
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In: Diabetologia. - : Springer Science and Business Media LLC. - 1432-0428 .- 0012-186X. ; 39:11, s. 1313-1317
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Journal article (peer-reviewed)abstract
- Some insulin-dependent diabetic (IDDM) patients develop severe forms of retinopathy. Putative risk factors such as hypertension, poor metabolic control, nephropathy and growth hormone levels do not fully explain the progress of retinopathy in these patients. It has been discussed whether there is a genetic marker, since some diabetic patients without any known predisposing risk factors develop severe retinopathy and others do not. In the present study, HLA-DR and DQ were compared in two patient groups with IDDM. One group consisted of patients with early-onset diabetes, with severe non-proliferative or proliferative retinopathy; the other group had no or only mild signs of retinopathy. High resolution HLA typing was carried out by polymerase chain reaction (PCR) and hybridization with allele specific probes. Alleles on the DR3-DQ2 haplotype, DRB1*0301, DQA1*0501 and DQB1*0201, were more frequent in patients with severe retinopathy. A difference was seen when combining certain alleles in the genotypes of DQA1*03/0501 (p > 0.05) and DQB1*0201/0302 (p < 0.01). The findings of the present study suggest that DQB1*0201/0302 is the strongest genetic marker for severe retinopathy and DRB1*0301/0401 only has a secondary influence when combined with this genotype. It seems as if IDDM patients who are positive for the genotype DR3-DQ2/DR4-DQ8 (DRB1*0301-DQA1*0501-DQB1*0201/DRB1*0401 -DQA1*03-DQB1*0302) are at greater risk of developing severe retinopathy.
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| 2. |
- Agardh, Daniel, et al.
(author)
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Inverse relationship between GAD65 antibody levels and severe retinopathy in younger type 1 diabetic patients
- 1998
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In: Diabetes Research and Clinical Practice. - 1872-8227. ; 40:1, s. 9-14
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Journal article (peer-reviewed)abstract
- Several risk factors for severe non-proliferative and proliferative retinopathy in type 1 diabetes mellitus have been proposed without explaining the rapid progression of retinopathy in some patients. Since GAD65 autoantibodies (GAD65Abs) are detected against glutamic acid decarboxylase (GAD), which is mainly expressed in islets and nervous tissue in type 1 diabetic patients, the aim of the present investigation was to test the hypothesis whether GAD65Abs are associated with rapidly progressing severe retinopathy. Patients with severe non-proliferative or proliferative retinopathy (n = 27) were compared with another group, which in spite of long diabetes duration had no or only mild signs of retinopathy (n = 28). GAD65Abs were analysed in a radioimmunoassay using in vitro translated human GAD65, and the levels were expressed as an index in relation to positive and negative reference samples. Using a cut-off level representing the 99th percentile of normals, 6/27 (22%) with and 9/28 (32%) without severe retinopathy were considered GAD65Ab positive. Although there was no difference in the number of GAD65Ab positive patients, the GAD65Ab levels were lower in patients with (0.30; 0.11-0.64) than without (0.68; 0.34-1.12) severe retinopathy (P = 0.03). The patients were also subjected to HLA-DR and DQ typing by PCR and hybridization with oligospecific probes. DQ2/8 was more common in patients with (56%) than without (29%) severe retinopathy (P = 0.05), but DQ2/8 could not account for the lower GAD65Ab levels in patients with severe retinopathy. It is concluded that GAD65Ab levels are inversely correlated with severe retinopathy in young type 1 diabetic patients.
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| 3. |
- Almqvist, Nils, et al.
(author)
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Methods for fabricating and characterizing a new generation of biomimetic materials
- 1999
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In: Materials science & engineering. C, biomimetic materials, sensors and systems. - 0928-4931 .- 1873-0191. ; 7:1, s. 37-43
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Journal article (peer-reviewed)abstract
- Bringing together current ideas in the fields of biomineralization and composite laminate materials, we have attempted to fabricate model materials that mimic abalone nacre through the rapid assembly of inorganic tablets, such as talc. Several physical methods were tested to aid the orientation of the talc tablets in fluid suspensions with a low percentage, 10% by dry weight, of organic binding material. The orientation of talc tablets in the synthesized composites was characterized by X-ray diffraction and scanning electron microscopy. The modulus of rupture of the materials was measured in a three-point bending test. We demonstrate that the alignment of tablets increases by the use of physical methods and from chemical surface treatment. Important factors to consider in making materials that mimic abalone nacre are discussed. Important factors to consider in making materials that mimic abalone nacre are discussed.
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| 4. |
- Bremer, Kåre, et al.
(author)
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An ordinal classification for the families of flowering plants
- 1998
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In: ANNALS OF THE MISSOURI BOTANICAL GARDEN. - : MISSOURI BOTANICAL GARDEN. - 0026-6493. ; 85:4, s. 531-553
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Journal article (other academic/artistic)abstract
- Recent cladistic analyses are revealing the phylogeny of flowering plants in increasing detail, and there is support for the monophyly of many major groups above the family level. With many elements of the major branching sequence of phylogeny established
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| 5. |
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| 6. |
- Lastras-Martínez, L. F., et al.
(author)
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Reflectance difference spectroscopy of GaAs asymmetric surface quantum wells above the fundamental gap
- 1998
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In: Physica status solidi. A, Applied research. - 0031-8965 .- 1521-396X. ; 170:2, s. 317-321
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Journal article (peer-reviewed)abstract
- We report Reflectance Difference (RD) measurement on (001) GaAs surface quantum wells (QW) under Ultra High Vacuum (UHV) conditions from 1.7 to 5.0eV. The QW is embedded between an arsenic-rich reconstructed GaAs surface and an AlAs barrier. The samples, grown by MBE with a protective arsenic cap layer, were heated to 320 and 430°C to desorb the As layer and form c(4 x 4) and (2 x 4) surface reconstructions, respectively. By modifying the surface reconstructure, we are able to separate the contributions to the optical anisotropy from the surface region (mainly associated with the As dimers) from those originating below the surface.
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| 7. |
- Rönnow, Daniel, et al.
(author)
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Surface Roughness Effects in Ellipsometry: Comparison of Truncated Sphere and Effective Medium Models
- 1995
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In: Optical materials (Amsterdam). - : Elsevier BV. - 0925-3467 .- 1873-1252. ; 4:6, s. 815-821
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Journal article (peer-reviewed)abstract
- We investigate the applicability of effective medium models for describing the effects of surface roughness on ellipsometric data. The ellipsometric parameters of a model surface composed of truncated spherical bumps on a substrate were calculated and compared to the Bruggeman effective medium theory. It is possible to fit the model calculations with the Bruggeman theory. However, the thickness and volume fraction of the effective medium layer describing the surface roughness do not correspond to the physical height and volume fraction of the bumps on the model surface.
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| 8. |
- Schäffer, Tilman E, et al.
(author)
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Does abalone nacre form by heteroepitaxial nucleation or by growth through mineral bridges?
- 1997
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In: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 9:8, s. 1731-1740
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Journal article (peer-reviewed)abstract
- We present experimental support for a model of abalone nacre growth that is based on mineral bridges between successive aragonite tablets rather than on heteroepitaxial nucleation. Interlamellar sheets of organic polymers delineate the aragonite tablets but allow the tablets to grow mineral bridges through pores in the sheets. Atomic force microscope images of interlamellar organic sheets from flat pearls made by Haliotis rufescens (red abalone; marine gastropod mollusk) reveal a fibrous core and holes of 5-50 nm in diameter. Scanning ion conductance microscopy shows that these holes are actually pores through the interlamellar sheets. With the help of statistical analysis we can associate the pore-to-pore spacings in the interlamellar sheets with the observed offsets of successive nacre tablets. These results, supplemented by AFM, SEM, and TEM images, support and extend the model of biofabrication of gastropod nacre which is based on mineral bridges between the aragonite tablets.
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