| 1. |
- Griss, P., et al.
(författare)
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Micromachined electrodes for biopotential measurements
- 2001
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Ingår i: Journal of microelectromechanical systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 1057-7157 .- 1941-0158. ; 10, s. 10-16
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Tidskriftsartikel (refereegranskat)abstract
- We describe the microfabrication, packaging and testing of a micromachined dry biopotential electrode, (i.e., where electrolytic gel is not required). It consists of an array of micro-dimensioned, very sharp spikes, (i.e., needles) designed for penetration of human skin which circumvent high impedance problems associated with layers of tbe outer skin. The spikes are etched in silicon by deep reactive ion etching and are subsequently covered with a silver-silverchloride (Ag-AgCl) double layer. The electrode-skin-electrode impedance of dry spiked electrodes having a size of 4 x 4 mm(2) is reduced compared to standard electrodes using electrolytic gel and having a comparable size, Recorded low amplitude biopotentials resulting from the activity of the brain, (i.e, EEG signals) are of high quality, even for spiked electrodes as small as 2 x 2 mm(2). The spiked electrode offers a promising alternative to standard electrodes in biomedical applications and is of interest in research of nem biomedical methods.
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| 2. |
- Iacobaeus, Christian, et al.
(författare)
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A novel portal imaging device for advanced radiation therapy
- 2001
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Ingår i: Nuclear Science, IEEE Transactions on. - Nuclear Science, IEEE Transactions on : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9499 .- 1558-1578. ; 48:4, Part 2, s. 1496-1502
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Tidskriftsartikel (refereegranskat)
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| 3. |
- Doverskog, Magnus, et al.
(författare)
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Cell cycle progression in serum-free cultures of Sf9 insect cells : Modulation by conditioned medium factors and implications for proliferation and productivity
- 2000
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Ingår i: Biotechnology progress (Print). - : Wiley. - 8756-7938 .- 1520-6033. ; 16:5, s. 837-846
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Tidskriftsartikel (refereegranskat)abstract
- Cell cycle progression was studied in serum-free batch cultures of Spodoptera frugiperda (Sf9) insect cells, and the implications for proliferation and productivity were investigated. Cell cycle dynamics in KBM10 serum-free medium was characterized by an accumulation of 50-70% of the cells in the G(2)/M phase of the cell cycle during the first 24 h after inoculation. Following the cell cycle arrest, the cell population was redistributed into G(1) and in particular into the S phase. Maximum rate of proliferation (mu(N,max)) was reached 24-48 h after the release from cell cycle arrest, coinciding with a minimum distribution of cells in the G(2)/M phase. The following declining mu(N) could be explained by a slow increase in the G(2)/M cell population. However, at approximately 100 h, an abrupt increase in the amount of G(2)/M cells occurred. This switch occurred at about the same time point and cell density, irrespective of medium composition and maximum cell density. An octaploid population evolved from G(2)/M arrested cells, showing the occurrence of endoreplication in this cell line. In addition, conditioned medium factor(s) were found to increase mu(N,max), decrease the time to reach mu(N,max), and decrease the synchronization of cells in G(2)/M during the lag and growth phase. A conditioned medium factor appears to be a small peptide. On basis of these results we suggest that the observed cell cycle dynamics is the result of autoregulatory events occurring at key points during the course of a culture, and that entry into mitosis is the target for regulation. Infecting the Sf9 cells with recombinant baculovirus resulted in a linear increase in volumetric productivity of beta-galactosidase up to 68-75 h of culture. Beyond this point almost no product was formed. Medium renewal at the time of infection could only partly restore the lost hypertrophy and product yield of cultures infected after the transition point. The critical time of infection correlated to the time when the mean;population cell volume had attained a minimum, and this occurred 24 h before the switch into the G(2)/M phase. We suggest that the cell density dependent decrease in productivity ultimately depends on the autoregulatory events leading to G(2)/M cell cycle arrest.
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| 4. |
- Ericson, Marica, 1974, et al.
(författare)
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Photodynamic therapy of actinic keratosis at varying fluence rates : Assessment of photobleaching, pain and primary clinical outcome
- 2004
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Ingår i: British Journal of Dermatology. - : Oxford University Press (OUP). - 0007-0963 .- 1365-2133. ; 151, s. 1204-1212
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Tidskriftsartikel (refereegranskat)abstract
- Background: Although photodynamic therapy (PDT) is becoming an important treatment method for skin lesions such as actinic keratosis (AK) and superficial basal cell carcinoma, there are still discussions about which fluence rate and light dose are preferable. Recent studies in rodents have shown that a low fluence rate is preferable due to depletion of oxygen at high fluence rates. However, these results have not yet been verified in humans. Objectives: The objective was to investigate the impact of fluence rate and spectral range on primary treatment outcome and bleaching rate in AK using aminolaevulinic acid PDT. In addition, the pain experienced by the patients has been monitored during treatment. Patients/methods Thirty-seven patients (mean age 71 years) with AK located on the head, neck and upper chest were treated with PDT, randomly allocated to four groups: two groups with narrow filter (580-650 nm) and fluence rates of 30 or 45 mW cm-2, and two groups with broad filter (580-690 nm) and fluence rates of 50 or 75 mW cm-2. The total cumulative light dose was 100 J cm-2 in all treatments. Photobleaching was monitored by fluorescence imaging, and pain experienced by the patients was registered by using a visual analogue scale graded from 0 (no pain) to 10 (unbearable pain). The primary treatment outcome was evaluated at a follow-up visit after 7 weeks. Results: Our data showed a significant correlation between fluence rate and initial treatment outcome, where lower fluence rate resulted in favourable treatment response. Moreover, the photo-bleaching dose (1/e) was found to be related to fluence rate, ranging from 4.5 ± 1.0 J cm -2 at 30 mW cm-2, to 7.3 ± 0.7 J cm-2 at 75 mW cm-2, indicating higher oxygen levels in tissue at lower fluence rates. After a cumulative light dose of 40 J cm-2 no further photobleaching took place, implying that higher doses are excessive. No significant difference in pain experienced by the patients during PDT was observed in varying the fluence rate from 30 to 75 mW cm-2. However, the pain was found to be most intense up to a cumulative light dose of 20 J cm-2. Conclusions: Our results imply that the photobleaching rate and primary treatment outcome are dependent on fluence rate, and that a low fluence rate (30 mW cm-2) seems preferable when performing PDT of AK using noncoherent light sources.
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| 5. |
- Gosch, M., et al.
(författare)
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Parallel single molecule detection with a fully integrated single-photon 2X2 CMOS detector array
- 2004
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Ingår i: Journal of Biomedical Optics. - : SPIE-Intl Soc Optical Eng. - 1083-3668 .- 1560-2281. ; 9:5, s. 913-921
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Tidskriftsartikel (refereegranskat)abstract
- We present parallel single molecule detection (SMD) and fluorescence correlation spectroscopy (FCS) experiments with a fully integrated complementary metal oxide semiconductor (CMOS) single-photon 2 X 2 detector array. Multifocal excitation is achieved with a diffractive optical element (DOE). Special emphasis is placed on parallelization of the total system. The performance of the novel single-photon CMOS detector is investigated and compared to a state-of-the-art single-photon detecting module [having an actively quenched avalanche photodiode (APD)] by measurements on free diffusing molecules at different concentrations. Despite the order of magnitude lower detection efficiency of the CMOS detector compared to the state-of-the-art single-photon detecting module, we achieve single molecule sensitivity and reliably determine molecule concentrations. In addition, the CMOS detector performance for the determination of the fraction of slowly diffusing molecules in a primer solution (two-component analysis) is demonstrated. The potential of this new technique for high-throughput confocal-detection-based systems is discussed.
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| 6. |
- Lawson, P A, et al.
(författare)
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Actinomyces funkei sp. nov., isolated from human clinical specimens.
- 2001
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Ingår i: International journal of systematic and evolutionary microbiology. - : Microbiology Society. - 1466-5026 .- 1466-5034. ; 51:Pt 3, s. 853-5
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Tidskriftsartikel (refereegranskat)abstract
- Three strains of a previously undescribed Actinomyces-like bacterium were isolated from human clinical specimens. Phenotypic studies indicated that the strains were members of the genus Actinomyces and were presumptively identified as Actinomyces turicensis. Comparative 16S rRNA gene sequencing studies showed that although the bacterium is phylogenetically closely related to Actinomyces turicensis, it nevertheless constitutes a new sub-line within the genus Actinomyces. Based on phenotypic and molecular chemical and molecular genetic evidence, it is proposed that the unknown Actinomyces-like bacterium from human clinical specimens be classified as Actinomyces funkei sp. nov. The type strain of Actinomyces funkei is CCUG 42773T (= CIP 106713T).
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| 7. |
- Mårtensson, Olof, et al.
(författare)
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Effects of fermented, ropy, non-dairy, oat-based products on serum lipids and the faecal excretion of cholesterol and short chain fatty acids in germfree and conventional rats
- 2002
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Ingår i: Nutrition Research. - 0271-5317. ; 22:12, s. 1461-1473
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Tidskriftsartikel (refereegranskat)abstract
- Three fermented, ropy, non-dairy, oat-based products were evaluated for their effect on serum lipids, faecal cholesterol and faecal short chain fatty. acids in germfree and conventional rats. Three different exopolysaccharide (EPS) producing lactic acid bacteria strains were used to ferment the non-dairy oat-base (Adavena(R) G40) (Ceba Foods AB, Lund; Sweden). Two commercial non-dairy products based on oats (Mill Milk(TM)) (Ceba Foods AB, Lund, Sweden) and rice (Rice Dream(R)) (Imagine Foods, London, UK) were used as non-ropy and unfermented controls. All the standardized feeds were sterilized before being fed to the animals. Adult, germfree-and conventional AGUS rats, were fed the above sterile diets ad libitum for 21 days. Blood samples and faecal samples were collected and the animals' weight gain was monitored throughout the study. No significant change in serum lipids or faecal excretion of cholesterol was observed between the groups on the different diets. A difference in faecal SCFA pattern was observed in conventional rats fed on the oat-based diets in comparison. to the group fed on the rice-based diet. More evidence is needed to support the effect of fermented, ropy, oat-based products and their potential effect on serum lipids, faecal cholesterol/coprostanol levels and amounts of short chain fatty acids.
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| 8. |
- Unneberg, Per, et al.
(författare)
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Transcript identification by analysis of short sequence tags-influence of tag length, restriction site and transcript database
- 2003
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Ingår i: Nucleic Acids Research. - : Oxford University Press (OUP). - 0305-1048 .- 1362-4962. ; 31:8, s. 2217-2226
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Tidskriftsartikel (refereegranskat)abstract
- There exist a number of gene expression profiling techniques that utilize restriction enzymes for generation of short expressed sequence tags. We have studied how the choice of restriction enzyme influences various characteristics of tags generated in an experiment. We have also investigated various aspects of in silico transcript identification that these profiling methods rely on. First, analysis of 14 248 mRNA sequences derived from the RefSeq transcript database showed that 1-30% of the sequences lack a given restriction enzyme recognition site. Moreover, 1-5% of the transcripts have recognition sites located less than 10 bases from the poly(A) tail. The uniqueness of 10 bp tags lies in the range 90-95%, which increases only slightly with longer tags, due to the existence of closely related transcripts. Furthermore, 3-30% of upstream 10 bp tags are identical to 3′ tags, introducing a risk of misclassification if upstream tags are present in a sample. Second, we found that a sequence length of 16-17 bp, including the recognition site, is sufficient for unique transcript identification by BLAST based sequence alignment to the UniGene Human non-redundant database. Third, we constructed a tag-to-gene mapping for UniGene and compared it to an existing mapping database. The mappings agreed to 79-83%, where the selection of representative sequences in the UniGene clusters is the main cause of the disagreement. The results of this study may serve to improve the interpretation of sequence-based expression studies and the design of hybridization arrays, by identifying short tags that have a high reliability and separating them from tags that carry an inherent ambiguity in their capacity to discriminate between genes. To this end, supplementary information in the form of a web companion to this paper is located at http://biobase.biotech.kth.se/tagseq.
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| 9. |
- Woestenenk, Esmeeralda A., et al.
(författare)
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Screening methods to determine biophysical properties of proteins in structural genomics
- 2003
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Ingår i: Analytical biochemistry. - 0003-2697. ; 318:1, s. 71-79
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Tidskriftsartikel (refereegranskat)abstract
- We have developed and tested a simple and efficient protein purification method for biophysical screening of proteins and protein fragments by nuclear magnetic resonance (NMR) and optical methods, such as circular dichroism spectroscopy. The method constitutes an extension of previously described protocols for gene expression and protein solubility screening [M. Hammarström et al., (2002), Protein Science 11, 313]. Using the present purification scheme it is possible to take several target proteins, produced as fusion proteins, from cell pellet to NMR spectrum and obtain a judgment on the suitability for further structural or biophysical studies in less than 1 day. The method is independent of individual protein properties as long as the target protein can be produced in soluble form with a fusion partner. Identical procedures for cell culturing, lysis, affinity chromatography, protease cleavage, and NMR sample preparation then initially require only optimization for different fusion partner and protease combinations. The purification method can be automated, scaled up or down, and extended to a traditional purification scheme. We have tested the method on several small human proteins produced in Escherichia coli and find that the method allows for detection of structured proteins and unfolded or molten globule-like proteins.
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| 10. |
- Aare, Magnus, et al.
(författare)
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Injury tolerances for oblique impact helmet testing
- 2004
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Ingår i: International Journal of Crashworthiness. - : Informa UK Limited. - 1358-8265 .- 1754-2111. ; 9:1, s. 15-23
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Tidskriftsartikel (refereegranskat)abstract
- The most frequently sustained severe injuries in motorcycle crashes are injuries to the head, and many of these are caused by rotational force. Rotational force is most commonly the result of oblique impacts to the head. Good testing methods for evaluating the effects of such impacts are currently lacking. There is also a need for improving our understanding of the effects of oblique impacts on the human head. Helmet standards currently in use today do not measure rotational effects in test dummy heads. However rotational force to the head results in large shear strains arising in the brain, which has been proposed as a cause of traumatic brain injuries like diffuse axonal injuries (DAI). This paper investigates a number of well-defined impacts, simulated using a detailed finite element (FE) model of the human head, an FE model of the Hybrid III dummy head and an FE model of a helmet. The same simulations were performed on both the FE human head model and the FE Hybrid III head model, both fitted with helmets. Simulations on both these heads were performed to describe the relationship between load levels in the FE Hybrid III head model and strains in the brain tissue in the FE human head model. In this study, the change in rotational velocity and the head injury criterion (HIC) value were chosen as appropriate measurements. It was concluded that both rotational and translational effects are important when predicting the strain levels in the human brain.
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