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| 2. |
- Stronati, A., et al.
(författare)
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Relationships between sperm DNA fragmentation, sperm apoptotic markers and serum levels of CB-153 and p,p '-DDE in European and Inuit populations
- 2006
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Ingår i: Reproduction. - : Bioscientifica. - 1470-1626 .- 1741-7899. ; 132:6, s. 949-958
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Tidskriftsartikel (refereegranskat)abstract
- Persistent organochlorine pollutants (POPs) are suspected to interfere with hormone activity and the normal homeostasis of spermatogenesis. We investigated the relationships between sperm DNA fragmentation, apoptotic markers identified on ejaculated spermatozoa and POP levels in the blood of 652 adult males (200 Inuits from Greenland, 166 Swedish, 134 Polish and 152 Ukrainian). Serum levels of 2, 2', 4, 4', 5, 5'-hexachlorobiphenyl (CB-153), as a proxy of the total POP burden, and of 1,1-dichloro-2,2-bis(p-chlorophenyl)-ethylene (p,p'-DDE), as a proxy of the total DDT exposure were determined. Sperm DNA fragmentation was measured by using the TUNEL assay, whereas immunofluorescence methods were utilized for detecting proapoptotic (Fas) and anti-apoptotic (Bcl-xL) markers. Both TUNEL assay and apoptotic markers were statistically differed across the four populations. No correlation between neither sperm DNA fragmentation nor apoptotic sperm parameters and the large variations in POPs exposure was observed for the separate study groups. However, considering the European populations taken together, we showed that both %TUNEL positivity and Bcl-xL were related to CB-153 serum levels, whereas our study failed to demonstrate any relations between DDE and %TUNEL positivity and apoptotic sperm biomarkers (Fas and Bcl-xL) in any region or overall regions. These results suggest that CB-153 and related chemicals might alter sperm DNA integrity and Bcl-xL levels in European adult males, but not in the highly exposed Inuit men. Additional issues (genetic background, lifestyle habits and characterization of total xeno-hormonal activities) need to he investigated in order to fully assess the population variations observed.
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- Larsen, A. Nylandsted, et al.
(författare)
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E center in silicon has a donor level in the band gap
- 2006
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 97:10, s. 106402/1-106402/4
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Tidskriftsartikel (refereegranskat)abstract
- It has been an accepted fact for more than 40 years that the E center in Si (the group-V impurity-vacancy pair)-one of the most studied defects in semiconductors-has only one energy level in the band gap: namely, the acceptor level at about 0.45 eV below the conduction band. We now demonstrate that it has a second level, situated in the lower half of the band gap at 0.27 eV above the valence band. The existence of this level, having a donor character, is disclosed by a combination of different transient-capacitance techniques and electronic-structure calculations. The finding seriously questions some diffusion-modeling approaches performed in the past.
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- Svendsen, S W, et al.
(författare)
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Task based exposure assessment in ergonomic epidemiology : a study of upper arm elevation in the jobs of machinists, car mechanics, and house painters.
- 2005
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Ingår i: Occupational and Environmental Medicine. - : BMJ. - 1351-0711 .- 1470-7926. ; 62:1, s. 18-27
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: To explore the precision of task based estimates of upper arm elevation in three occupational groups, compared to direct measurements of job exposure. METHODS: Male machinists (n = 26), car mechanics (n = 23), and house painters (n = 23) were studied. Whole day recordings of upper arm elevation were obtained for four consecutive working days, and associated task information was collected in diaries. For each individual, task based estimates of job exposure were calculated by weighting task exposures from a collective database by task proportions according to the diaries. These estimates were validated against directly measured job exposures using linear regression. The performance of the task based approach was expressed through the gain in precision of occupational group mean exposures that could be obtained by adding subjects with task based estimates to a group of subjects with measured job exposures in a "validation" design. RESULTS: In all three occupations, tasks differed in mean exposure, and task proportions varied between individuals. Task based estimation proved inefficient, with squared correlation coefficients only occasionally exceeding 0.2 for the relation between task based and measured job exposures. Consequently, it was not possible to substantially improve the precision of an estimated group mean by including subjects whose job exposures were based on task information. CONCLUSIONS: Task based estimates of mechanical job exposure can be very imprecise, and only marginally better than estimates based on occupation. It is recommended that investigators in ergonomic epidemiology consider the prospects of task based exposure assessment carefully before placing resources at obtaining task information. Strategies disregarding tasks may be preferable in many cases
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| 5. |
- Toft, G, et al.
(författare)
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Menstrual cycle characteristics in European and Inuit women exposed to persistent organochlorine pollutants
- 2008
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Ingår i: Human Reproduction. - : Oxford University Press (OUP). - 0268-1161 .- 1460-2350. ; 23:1, s. 193-200
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND Previous inconsistent results suggest that menstrual cycles may be disturbed by exposure to polychlorinated biphenyls (PCBs) and 1,1-dichloro-2,2-bis (p-chlorophenyl)-ethylene (DDE). METHODS Information on menstrual cycle characteristics were obtained by questionnaires, and PCB and DDE were measured in serum samples from a total of 1494 women from Greenland, Swedish fishermen's wives, and inhabitants of Warsaw in Poland and Kharkiv in Ukraine. RESULTS No consistent effects of PCB and DDE exposure on menstrual cycle characteristics were observed across populations. Within populations, we observed increased risks of short cycles (/=32 days) among Polish women exposed to high levels of DDE (OR 3.1, CI 1.1-8.6). However, in Greenland it seemed that high levels of PCB or DDE were protective against long menstrual cycles (OR 0.7 CI 0.5-0.96 and OR 0.7 CI 0.5-0.99, respectively). CONCLUSIONS It is unlikely that exposure to PCB and DDE is a main cause of menstrual disturbances. Genetic differences or dietary factors may be involved in the non-homogenous associations of organochlorine exposure and menstrual cycle between countries.
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