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| 2. |
- Garberg, Per, et al.
(författare)
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Binding of tellurium to hepatocellular selenoproteins during incubationwith inorganic tellurite : consequences for the activity ofselenium-dependent glutathione peroxidase
- 1999
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Ingår i: International Journal of Biochemistry and Cell Biology. - 1357-2725 .- 1878-5875. ; 31:2, s. 291-301
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Tidskriftsartikel (refereegranskat)abstract
- The metallic group XVIa elements selenium and tellurium possess remarkably similar chemical properties. However, unlike selenium, tellurium is not an essential micronutrient and, indeed, induces both acute and chronic toxicity in a variety of species. Despite this, very little is known of the molecular mechanisms of toxicity of tellurium, particularly with respect to potential chemical interactions with selenium-containing components in the cell. In this work we describe a novel interaction of inorganic tellurite with hepatocellular selenoproteins, particularly with selenium-dependent glutathione peroxidase. The accumulation of (121Te)-tellurite into cultured primary rat liver hepatocytes was shown to be much more rapid than that of (75Se)-selenite on a molar basis. Neither the uptake of (121Te)-tellurite nor of (75Se)-selenite was affected by a large molar excess of the unlabelled counterpart, respectively. Interestingly, separation of the hepatocellular proteins on continuous pH denaturing gels demonstrated clear binding of radiolabelled tellurium to a number of protein bands, including one at 23 and one at 58 kDa, which corresponded to proteins readily labelled in cells treated with (75Se)-selenite. The binding of (121Te) to these proteins was insensitive to reduction with mercaptoethanol and not affected by pre-treatment of the cells with cycloheximide. When purified selenium-dependent glutathione peroxidase was treated directly with (121Te)-tellurite, the protein became labelled in an analogous manner to that achieved in intact cells. This was not affected by coincubation of the enzyme with (121Te)-tellurite and one or both of its substrates. Additionally, incubation of the peroxidase with tellurite effectively inhibited its ability to catalyse glutathione-dependent reduction of hydrogen peroxide. These data suggest that inorganic tellurite delivers tellurium to the intracellular milieu in a form capable of binding to some intracellular selenoproteins and at least in the case of glutathione peroxidase, cause inhibition of catalytic activity. The nature of the binding seems not to be due to the insertion of tellurocysteine into the protein and the insensitivity to reductive cleavage with mercaptoethanol seems to preclude the formation of stable telluro-selenides in the proteins. These data may offer alternative explanations for the established toxicity of tellurium via disruption of selenoprotein function, particularly by the induction of intracellular oxidative stress by the inhibition of Se-dependent glutathione peroxidase.
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| 3. |
- Gerdes, S, et al.
(författare)
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Effect of surface structure on the spreading of a PDMS droplet
- 1998
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Ingår i: Langmuir. - 0743-7463 .- 1520-5827. ; 14, s. 7052-5057
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Tidskriftsartikel (refereegranskat)abstract
- The effect of surface structures on the dynamics of wetting was investigated through measurements of the dynamic contact angle and spreading velocity of a PDMS droplet spreading over a surface with a gridlike pattern of V-shaped surface channels. A rim of liquid was observed to spread out in the channels ahead of the dropfront after a short time of spreading (seconds). The characteristics of the rim were investigated as well, with respect to channel depth and spacing and compared to the spreading characteristics in channels with no intersections, i.e. parallel channels. The macroscopic droplet appears to be dependent on the rim for spreading, before the rim had appeared the dropfront spread stepwise between the perpendicular channels and did not advance until the channel was liquid filled. The spreading on the filled channels was correlated to the surface area covered by channels rather than the depth and width of the individual channel. The spreading of the rim follows the expected scaling with (time)1/2 and (channel depth)1/2 ..
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| 4. |
- Gerdes, S, et al.
(författare)
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Spreading of oil droplets on silicon oxide surfaces with parallel v-shaped channels
- 1996
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Ingår i: Colloids and Surfaces B. - 0927-7765 .- 1873-4367. ; 116, s. 135-144
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Tidskriftsartikel (refereegranskat)abstract
- The spreading of silicone oil and paraffin oil has been studied on two energetically and chemically different smooth surfaces (gold and polystyrene). It was found that for these surfaces neither the surface tension nor the surface free energy influenced the spreading behaviour of the oils. The data for the two different liquids can be transposed onto a master curve when the product of velocity and viscosity is plotted versus the dynamic contact angle. Spreading of paraffin oil droplets where also studied on a set of silicone oxide surfaces containing parallel v-shaped surface channels at various widths and spacings. It was found that the sharp edges of the channel walls strongly affected spreading and that droplet shape was distorted from the usual circular shape displayed on a smooth surface. Ån elongated droplet was formed with the contact line following a channel edge and with the short sides having a semi-circular shape. Traverse spreading was very slow and decreased as the spacing was decreased. Increased channel size and decreased spacing produced an increase in spreading velocity in the direction of the channels.
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| 5. |
- Gerdes, S, et al.
(författare)
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The spreading of silicone oil droplets on a surface with parallel V-shaped grooves
- 1997
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Ingår i: Langmuir. - 0743-7463 .- 1520-5827. ; 13, s. 7258-7264
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we report on dynamic wetting studies on model rough surfaces. A series of well-defined model surfaces has been manufactured and the dynamic wetting of silicone oil droplets on these surfaces has been studied. The surface structures are etched parallel v-shaped grooves with varying width and spacing. Spreading has been studied in two different time regimes with two different techniques. At "short times", the liquid does not penetrate significantly inside the grooves ahead of the edge of the main drop. At "long times", the penetration of liquid inside the grooves is significant and the grooves are practically filled up at the edge of the main drop, which we consider as the "contact line". In both regimes, contact line velocity, v, and dynamic contact angle, q, are measured in the flat parts between grooves. The spreading parallel to the grooves is described by Tanner-like laws in both cases, but with different characteristics: At short times, the spreading velocity increases with the area covered by grooves. At long times no effect of the grooves are observed until the distance between the grooves are smaller than approximately 30µm. In this case, it appears that the effect is correlated with the disturbance of the contact line due to the interaction of the groove 'defects'.
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| 6. |
- Hakansson, Sara, et al.
(författare)
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Moderate frequency of BRCA1 and BRCA2 germ-line mutations in Scandinavian familial breast cancer
- 1997
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Ingår i: American Journal of Human Genetics. - 0002-9297. ; 60:5, s. 1068-1078
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies of high-risk breast cancer families have proposed that two major breast cancer-susceptibility genes, BRCA1 and BRCA2, may account for at least two-thirds of all hereditary breast cancer. We have screened index cases from 106 Scandinavian (mainly southern Swedish) breast cancer and breast-ovarian cancer families for germ-line mutations in all coding exons of the BRCA1 and BRCA2 genes, using the protein-truncation test, SSCP analysis, or direct sequencing. A total of 24 families exhibited 11 different BRCA1 mutations, whereas 11 different BRCA2 mutations were detected in 12 families, of which 3 contained cases of male breast cancer. One BRCA2 mutation, 4486delG, was found in two families of the present study and, in a separate study, also in breast tumors from three unrelated males with unknown family history, suggesting that at least one BRCA2 founder mutation exists in the Scandinavian population. We report 1 novel BRCA1 mutation, eight additional cases of 4 BRCA1 mutations described elsewhere, and 11 novel BRCA2 mutations (9 frameshift deletions and 2 nonsense mutations), of which all are predicted to cause premature truncation of the translated products. The relatively low frequency of BRCA1 and BRCA2 mutations in the present study could be explained by insufficient screening sensitivity to the location of mutations in uncharacterized regulatory regions, the analysis of phenocopies, or, most likely, within predisposed families, additional uncharacterized BRCA genes.
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