| 1. |
- Beral, V, et al.
(author)
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Alcohol, tobacco and breast cancer - collaborative reanalysis of individual data from 53 epidemiological studies, including 58515 women with breast cancer and 95067 women without the disease
- 2002
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In: British Journal of Cancer. - : Springer Science and Business Media LLC. - 1532-1827 .- 0007-0920. ; 87, s. 1234-45
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Journal article (peer-reviewed)abstract
- Alcohol and tobacco consumption are closely correlated and published results on their association with breast cancer have not always allowed adequately for confounding between these exposures. Over 80% of the relevant information worldwide on alcohol and tobacco consumption and breast cancer were collated, checked and analysed centrally. Analyses included 58515 women with invasive breast cancer and 95067 controls from 53 studies. Relative risks of breast cancer were estimated, after stratifying by study, age, parity and, where appropriate, women's age when their first child was born and consumption of alcohol and tobacco. The average consumption of alcohol reported by controls from developed countries was 6.0 g per day, i.e. about half a unit/drink of alcohol per day, and was greater in ever-smokers than never-smokers, (8.4 g per day and 5.0 g per day, respectively). Compared with women who reported drinking no alcohol, the relative risk of breast cancer was 1.32 (1.19 - 1.45, P < 0.00001) for an intake of 35 - 44 g per day alcohol, and 1.46 (1.33 - 1.61, P < 0.00001) for greater than or equal to 45 g per day alcohol. The relative risk of breast cancer increased by 7.1% (95% CI 5.5-8.7%; P<0.00001) for each additional 10 g per day intake of alcohol, i.e. for each extra unit or drink of alcohol consumed on a daily basis. This increase was the same in ever-smokers and never-smokers (7.1 % per 10 g per day, P < 0.00001, in each group). By contrast, the relationship between smoking and breast cancer was substantially confounded by the effect of alcohol. When analyses were restricted to 22 255 women with breast cancer and 40 832 controls who reported drinking no alcohol, smoking was not associated with breast cancer (compared to never-smokers, relative risk for ever-smokers= 1.03, 95% CI 0.98 - 1.07, and for current smokers=0.99, 0.92 - 1.05). The results for alcohol and for tobacco did not vary substantially across studies, study designs, or according to 15 personal characteristics of the women; nor were the findings materially confounded by any of these factors. If the observed relationship for alcohol is causal, these results suggest that about 4% of the breast cancers in developed countries are attributable to alcohol. In developing countries, where alcohol consumption among controls averaged only 0.4 g per day, alcohol would have a negligible effect on the incidence of breast cancer. In conclusion, smoking has little or no independent effect on the risk of developing breast cancer; the effect of alcohol on breast cancer needs to be interpreted in the context of its beneficial effects, in moderation, on cardiovascular disease and its harmful effects on cirrhosis and cancers of the mouth, larynx, oesophagus and liver. (C) 2002 Cancer Research UK.
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| 2. |
- Enger, Jonas, et al.
(author)
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Direct detection of antimony in environmental and biological samples at trace concentrations by laser-induced fluorescence in graphite furnace with an intensified charge coupled device
- 1995
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In: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry. - 0267-9477 .- 1364-5544. ; 10:8, s. 539-549
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Journal article (peer-reviewed)abstract
- The technique of laser-induced fluorescence in graphite furnace (LIF-GF) with intensified charge coupled device (ICCD) detection was used for the detection of Sb at pg ml-1 concentrations in various biological and environmental samples. The ICCD detector permits the simultaneous multichannel detection of large fluorescence wavelength regions, which gives the user the possibility to control and correct for various background signals (which is important when complex environmental and biological samples are to be analysed). The detection limit for Sb in a pure water solution was found to be 5 fg. Antimony was directly detected in pure aqueous solutions down to fg ml-1 concentrations. A variety of aqueous and solid environmental and biological samples were investigated with respect to their Sb content. Good agreement between the measured and certified Sb contents (at pg ml-1 - ng ml-1 levels) was obtained for various certified reference materials, viz., marine sediments (MESS-1 and BCSS-1) and riverine water (SLRS-2). Measurements of the Sb content in non-certified natural drinking water, estuarine water reference material (SLEW-1), serum reference material (Seronorm), and whole blood of healthy Swedish people were also performed. After a thorough investigation and elimination of various sources of contamination (regarding sampling and sample storage), typical levels of Sb in human whole blood at or below several tens of pg ml-1 were obtained. These levels are significantly lower than previously established values of the normal Sb content in human blood. The detection limit for Sb in human whole blood was close to that of pure water.
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| 3. |
- Enger, Jonas, et al.
(author)
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Laser-induced fluorescence in a graphite furnace as a sensitive technique for assessment of traces in North Arctic atmospheric aerosol samples
- 1995
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In: The Analyst. - : Royal Society of Chemistry. - 0003-2654 .- 1364-5528. ; 120:3, s. 635-641
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Journal article (peer-reviewed)abstract
- An improved version of the highly sensitive laser-based spectroscopic trace-element detection technique, laser-induced fluorescence in a graphite furnace, LIF-GF (often also referred to as laser-excited atomic fluorescence spectrometry in electrothermal atomizer, ETA-LEAFS) has been used to assess the trace-element content of Al and Pb in size-fractionated aerosol samples from the Norwegian Arctic. The ordinary LIF-GF technique has been modified for improved selectivity by the incorporation of a multi-channel intensified CCD detector (ICCD) which mikes constant monitoring of various background signals possible (scattered laser light, concomitant fluorescence light, and black body radiation). It is shown that the sensitivity and selectivity of the LIF-GF-ICCD technique is sufficient for efficient detection of the trace contents of Al and Pb in dissolved aerosol samples from the Norwegian Arctic (0-75 pg for each furnace heating). The Al and Pb concentrations in air from Ny Alesund, Svalbard, at the time of sampling (March-April 1992) were found to be 1-50 ng m-3.
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| 4. |
- Enger, Jonas, 1966, et al.
(author)
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Optical tweezers applied to a microfluidic system
- 2004
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In: Lab on a Chip. - : Royal Society of Chemistry (RSC). - 1473-0197 .- 1473-0189. ; 4, s. 196-200
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Journal article (peer-reviewed)abstract
- We will demonstrate how optical tweezers can be combined with a microfluidic system to create a versatile microlaboratory. Cells are moved between reservoirs filled with different media by means of optical tweezers. We show that the cells, on a timescale of a few seconds, can be moved from one reservoir to another without the media being dragged along with them. The system is demonstrated with an experiment where we expose E. coli bacteria to different fluorescent markers. We will also discuss how the system can be used as an advanced cell sorter. It can favorably be used to sort out a small fraction of cells from a large population, in particular when advanced microscopic techniques are required to distinguish various cells. Patterns of channels and reservoirs were generated in a computer and transferred to a mask using either a sophisticated electron beam technique or a standard laser printer. Lithographic methods were applied to create microchannels in rubber silicon (PDMS). Media were transported in the channels using electroosmotic flow. The optical system consisted of a combined confocal and epi-fluorescence microscope, dual optical tweezers and a laser scalpel.
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| 5. |
- Eriksson, Emma, 1980, et al.
(author)
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A microfluidic system in combination with optical tweezers for analyzing rapid and reversible cytological alterations in single cells upon environmental changes
- 2007
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In: Lab on a chip. - : Royal Society of Chemistry (RSC). - 1473-0197 .- 1473-0189. ; 7:1, s. 71-76
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Journal article (peer-reviewed)abstract
- We report on the development of an experimental platform where epi-fluorescence microscopy and optical tweezers are combined with a microfluidic system to enable the analysis of rapid cytological responses in single cells. The microfluidic system allows two different media to be merged in a Y-shaped channel. Microscale channel dimensions ensure purely laminar flow and, as a result, an environmental gradient can be created between the two media. Optical tweezers are used to move a single trapped cell repeatedly between the different environments. The cell is monitored continuously by fluorescence microscopy during the experiment. In a first experiment on yeast (Saccharomyces cerevisiae) we observed changes in cell volume as the cell was moved between environments with different osmolarity. This demonstrated that the platform allowed analysis of cytological alterations on a time scale shorter than 0.2 s. In a second experiment we observed the spatial migration of the Yap1p transcription factor fused to GFP as a cell was moved from an environment of low to high oxidative capacity. The system is universal allowing the response to numerous environmental changes to be studied on the sub second time scale in a variety of model cells. We intend to use the platform to study how the age of cells, their progression through the cell cycle, or their genetic landscape, alter their capacity (kinetics and amplitude) to respond to environmental changes.
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| 6. |
- Eriksson, Emma, 1980, et al.
(author)
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Holographic optical tweezers combined with a microfluidic device for exposing cells to fast environmental changes
- 2007
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In: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X.
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Conference paper (peer-reviewed)abstract
- Optical manipulation techniques have become an important research tool for single cell experiments in microbiology. Using optical tweezers, single cells can be trapped and held during long experiments without risk of cross contamination or compromising viability. However, it is often desirable to not only control the position of a cell, but also to control its environment. We have developed a method that combines optical tweezers with a microfluidic device. The microfluidic system is fabricated by soft lithography in which a constant flow is established by a syringe pump. In the microfluidic system multiple laminar flows of different media are combined into a single channel, where the fluid streams couple viscously. Adjacent media will mix only by diffusion, and consequently two different environments will be separated by a mixing region a few tens of micrometers wide. Thus, by moving optically trapped cells from one medium to another we are able to change the local environment of the cells in a fraction of a second. The time needed to establish a change in environment depends on several factors such as the strength of the optical traps and the steepness of the concentration gradient in the mixing region. By introducing dynamic holographic optical tweezers several cells can be trapped and analyzed simultaneously, thus shortening data acquisition time. The power of this system is demonstrated on yeast (Saccharomyces cerevisiae) subjected to osmotic stress, where the volume of the yeast cell and the spatial localization of green fluorescent proteins (GFP) are monitored using fluorescence microscopy.
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| 7. |
- Eriksson, Emma, 1980, et al.
(author)
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Optical manipulation and microfluidics for studies of single cell dynamics
- 2007
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In: Journal of Optics. A, Pure and applied optics. - 1464-4258 .- 1741-3567 .- 1361-6617. ; 9:8, s. 113-121
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Journal article (peer-reviewed)abstract
- Most research on optical manipulation aims towards investigation and development of the system itself. In this paper we show how optical manipulation, imaging and microfluidics can be combined for investigations of single cells. Microfluidic systems have been fabricated and are used, in combination with optical tweezers, to enable environmental changes for single cells. The environment within the microfluidic system has been modelled to ensure control of the process. Three biological model systems have been studied with different combinations of optical manipulation, imaging techniques and microfluidics. In Saccharomyces cerevisiae, environmentally induced size modulations and spatial localization of proteins have been studied to elucidate various signalling pathways. In a similar manner the oxygenation cycle of single red blood cells was triggered and mapped using Raman spectroscopy. In the third experiment the forces between the endoplasmic reticulum and chloroplasts were studied in Pisum sativum and Arabidopsis thaliana. By combining different techniques we make advanced biological research possible, revealing information on a cellular level that is impossible to obtain with traditional techniques.
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| 8. |
- Galan, D., et al.
(author)
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A remote laboratory for optical levitation of charged droplets
- 2018
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In: European Journal of Physics. - : IOP Publishing. - 0143-0807 .- 1361-6404. ; 39:4
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Journal article (peer-reviewed)abstract
- We present a remotely controlled experiment in which liquid droplets are levitated by a vertically aligned focused laser beam. The droplets levitate at the point where the photon pressure of the focused laser beam balances the gravitational force. The size of a trapped droplet can be measured by detecting the diffraction pattern created by the trapping laser light. The charge on the trapped droplet can thereafter be determined by observing its motion when a vertically directed electrical field is applied. This experiment allows a student to study many fundamental physics processes, such as photon pressure, diffraction of light, or the motion of charged particles in electrical fields. The complexity of the experiments and the concept studied make this suitable for advanced studies in physics. The laser power required in the experiment is about 1 W, which is a thousand times greater than the value of 1 mW at which lasers begin to be capable of causing harm to eyes; high voltages are also used. Further, the cost of the equipment is relatively high, which limits its availability to most undergraduate teaching laboratories. It thus constitutes an ideal experiment for remote control.
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| 9. |
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| 10. |
- Goksör, Mattias, 1975, et al.
(author)
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Optical manipulation in combination with multiphoton microscopy for single-cell studies
- 2004
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In: Applied Optics. ; 43:25, s. 4831-4837
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Journal article (peer-reviewed)abstract
- We demonstrate how optical tweezers can be incorporated into a multiphoton microscope to achieve three-dimensional imaging of trapped cells. The optical tweezers, formed by a cw 1064 nm Nd:YVO4 laser, were used to trap live yeast cells in suspension while the 4′, 6-diamidino-2-phenylindole-stained nucleus was imaged in three dimensions by use of a pulsed femtosecond laser. The trapped cell was moved in the axial direction by changing the position of an external lens, which was used to control the divergence of the trapping laser beam. This gives us a simple method to use optical tweezers in the laser scanning of confocal and multiphoton microscopes. It is further shown that the same femtosecond laser as used for the multiphoton imaging could also be used as laser scissors, allowing us to drill holes in the membrane of trapped spermatozoa.
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