| 1. |
- Enfors, Sven-Olof, et al.
(författare)
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Physiological responses to mixing in large scale bioreactors
- 2001
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Ingår i: Journal of Biotechnology. - 0168-1656 .- 1873-4863. ; 85:2, s. 175-185
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Tidskriftsartikel (refereegranskat)abstract
- Escherichia coli fed-batch cultivations at 22 m(3) scale were compared to corresponding laboratory scale processes and cultivations using a scale-down reactor furnished with a high-glucose concentration zone to mimic the conditions in a feed zone of the large bioreactor. Formate accumulated in the large reactor, indicating the existence of oxygen limitation zones. It is suggested that the reduced biomass yield at large scale partly is due to repeated production/reassimilation of acetate from overflow metabolism and mixed acid fermentation products due to local moving zones with oxygen limitation. The conditions that generated mixed-acid fermentation in the scale-down reactor also induced a number of stress responses, monitored by analysis of mRNA of selected stress induced genes. The stress responses were relaxed when the cells returned to the substrate limited and oxygen sufficient compartment of the reactor. Corresponding analysis in the large reactor showed that the concentration of mRNA of four stress induced genes was lowest at the sampling port most distant from the feed zone. It is assumed that repeated induction/relaxation of stress responses in a large bioreactor may contribute to altered physiological properties of the cells grown in large-scale bioreactor. Flow cytometric analysis revealed reduced damage with respect to cytoplasmic membrane potential and integrity in cells grown in the dynamic environments of the large scale reactor and the scale-down reactor.
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| 2. |
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| 3. |
- Lindholm Dahlstrand, Åsa, et al.
(författare)
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Avknoppningsmöjligheter i industriföretag
- 1997
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Ingår i: Uppfinn framtiden - Förutsättningar för innovationer och entreprenörskap i sandens tidsålder.
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 4. |
- Allen, D.H., et al.
(författare)
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Modeling the viscoelastic response of GMT structural components
- 2001
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Ingår i: Composites Science And Technology. - 0266-3538 .- 1879-1050. ; 61:4, s. 503-515
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Tidskriftsartikel (refereegranskat)abstract
- A glass-mat-reinforced thermoplastic (GMT) composite material has been fabricated from randomly oriented continuous glass fibers embedded in a polypropylene matrix. The mechanical constitution of this composite has been characterized by using a linear viscoelastic micromechanically based material model. This material model has subsequently been implemented to several finite-element computer codes for analysis of structural components fabricated from polypropylene GMT. In this paper several example problems have been studied in order to determine the applicability of this modeling approach to predicting time-dependent deformations due to creep in GMT components. These example problems have been solved by utilizing two commercially available codes: ABAQUS, and ANSYS. Furthermore, results obtained with the codes have been compared to both analytic and experimental results, with varying degrees of success. The paper details these results for each of the example problems considered herein. © 2001 Elsevier Science Ltd. All rights reserved.
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| 5. |
- Luijsterburg, MS, et al.
(författare)
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Heterochromatin protein 1 is recruited to various types of DNA damage
- 2009
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Ingår i: The Journal of cell biology. - : Rockefeller University Press. - 1540-8140 .- 0021-9525. ; 185:4, s. 577-586
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Tidskriftsartikel (refereegranskat)abstract
- Heterochromatin protein 1 (HP1) family members are chromatin-associated proteins involved in transcription, replication, and chromatin organization. We show that HP1 isoforms HP1-α, HP1-β, and HP1-γ are recruited to ultraviolet (UV)-induced DNA damage and double-strand breaks (DSBs) in human cells. This response to DNA damage requires the chromo shadow domain of HP1 and is independent of H3K9 trimethylation and proteins that detect UV damage and DSBs. Loss of HP1 results in high sensitivity to UV light and ionizing radiation in the nematode Caenorhabditis elegans, indicating that HP1 proteins are essential components of DNA damage response (DDR) systems. Analysis of single and double HP1 mutants in nematodes suggests that HP1 homologues have both unique and overlapping functions in the DDR. Our results show that HP1 proteins are important for DNA repair and may function to reorganize chromatin in response to damage.
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| 6. |
- Marteijn, JA, et al.
(författare)
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Nucleotide excision repair-induced H2A ubiquitination is dependent on MDC1 and RNF8 and reveals a universal DNA damage response
- 2009
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Ingår i: The Journal of cell biology. - : Rockefeller University Press. - 1540-8140 .- 0021-9525. ; 186:6, s. 835-847
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Tidskriftsartikel (refereegranskat)abstract
- Chromatin modifications are an important component of the of DNA damage response (DDR) network that safeguard genomic integrity. Recently, we demonstrated nucleotide excision repair (NER)–dependent histone H2A ubiquitination at sites of ultraviolet (UV)-induced DNA damage. In this study, we show a sustained H2A ubiquitination at damaged DNA, which requires dynamic ubiquitination by Ubc13 and RNF8. Depletion of these enzymes causes UV hypersensitivity without affecting NER, which is indicative of a function for Ubc13 and RNF8 in the downstream UV–DDR. RNF8 is targeted to damaged DNA through an interaction with the double-strand break (DSB)–DDR scaffold protein MDC1, establishing a novel function for MDC1. RNF8 is recruited to sites of UV damage in a cell cycle–independent fashion that requires NER-generated, single-stranded repair intermediates and ataxia telangiectasia–mutated and Rad3-related protein. Our results reveal a conserved pathway of DNA damage–induced H2A ubiquitination for both DSBs and UV lesions, including the recruitment of 53BP1 and Brca1. Although both lesions are processed by independent repair pathways and trigger signaling responses by distinct kinases, they eventually generate the same epigenetic mark, possibly functioning in DNA damage signal amplification.
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| 7. |
- Åvall-Lundqvist, Elisabeth, et al.
(författare)
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Serum alkaline DNase activity in normal or nonhospitalised individuals.
- 1989
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Ingår i: Clinica Chimica Acta. - : Elsevier BV. - 0009-8981 .- 1873-3492. ; 185:1, s. 35-43
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Tidskriftsartikel (refereegranskat)abstract
- According to previous observations, the variations in serum alkaline DNase activity (SADA) appeared to be useful in monitoring malignant disease. In this study, SADA was measured in 625 individuals to explore nontumor-related factors which may influence SADA levels. The overall range in SADA was 0.2-82.3 kU/l. Women aged 50-79 years had higher (p less than 0.001) levels of SADA than younger females. A similar but less consistent effect of age was noticed in men (0.01 less than p less than 0.05). Older men had lower (0.01 less than p less than 0.05) SADA levels than the older women. Old women substituted with estrogens had lower (0.01 less than p less than 0.05) levels of SADA than those not treated with estrogens. SADA levels in pregnancy as well as postparturition were lower (p less than 0.001) than SADA values in nonpregnant females of similar age. In fertile women, no SADA variation was observed during the menstrual cycle and there was no significant effect of contraceptive pills. In males, SADA seemed unrelated to testosterone or cortisol levels but varied during the day. Smoking, alcohol consumption and drug therapy appeared to be without effect on SADA.
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