Cytogenetic analysis of 2928 CVS samples and 1075 amniocenteses from randomized studies

We report cytogenetic results from a randomized Danish chorionic villus sampling (CVS) and amniocentesis (AC) study including 2928 placental and 1075 amniotic fluid specimens processed in the same laboratory. The results are presented in groups comparing CVS with amniocentesis and transabdominal (TA) CVS with transcervical (TC) CVS as randomized. More abnormalities and more ambiguous diagnostic problems were found in placental tissues than in amniotic cells. There were no diagnostic errors and no incorrect sex predictions. Mosaicism was detected in 1 per cent of all cases of CVS (discordancies included). When confirmation studies were done, 90 per cent were found to be confined to the placenta. Eight cases (0.7 per cent) of mosaicism/pseudomosaicism were seen in amniotic fluid specimens, and two cases of five with confirmation studies were confirmed in the fetus. The rate of mosaicism/pseudomosaicism in CVS and AC specimens differed (P <0.05). The rate of pseudomosaicism in cultures of villi and amniotic fluid cells was 0.5 and 0.6 per cent, respectively. Single-cell aneuploidy was observed in 1.8 per cent of villi and 1.4 per cent of amniotic fluid cell specimens. Maternal cell contamination (MCC) was seen more often after TC sampling (4.5 per cent) compared with TA sampling (1.5 per cent), but posed no problems in interpretation. Compared with the processing of cultured specimens, the short-term method of preparation of villi in our laboratory doubled the technicians' workload. For practical and economic reasons we have ceased the routine use of short-term preparations.     

Development of a new masters program for occupational physicians in Flanders

Background: discussions with occupational physicians and a postal survey identified the shortcomings of previous programs, mainly found in the fields of occupational hygiene, ergonomics, environmental health and management.Objectives of the new program: basic knowledge (see content), the development of problem solving skills, scientific and social attitudes.Content: first year: occupational health practice, occupational hygiene, epidemiology, work physiology, toxicokinetics and dynamics and in service training (4 weeks). Second year: occupational pathology, environmental health, ergonomics, social legislation, safety, management and in service training (4 weeks). The total study load is estimated at about 1600 hours per year.Methods: interactivity is stimulated by the introduction of interdisciplinary seminars, project work in groups and Socratic dialogue. The objectives, contents and teaching and student-evaluation methods of the separate items were defined before selecting teachers.Finality of the program: a masters title sufficient to practice occupational medicine in Belgium. A subsequent postacademic training of 2 years, while at work, will be required for the title of specialist in occupational medicine, valid at European Union (EU) level. It will include preparing and publically defending a thesis.Statement: The collaboration of ex-students working in the field is essential in the development and quality assessment of adequate teaching programs.     

Global Climate Change and Sustainable Development

A simple low cost contact closure circuit has been developed to control an array of instruments for atmospheric trace species measurements. The modular design allows reconfiguration of existing instrumentation, addition of new instruments and troubleshooting, with minimum interruption to the ongoing measurements.     

Mineralisation studies of 14C-labelled metsulfuron-methyl, tribenuron-methyl, chlorsulfuron and thifensulfuron-methyl in one Danish soil and groundwater sediment profile.

Bacterial mineralisation of four sulfonylurea herbicides at 20 microg kg(-1) in a sandy soil from nine different depths in a sandy soil horizon (5-780 cm) was investigated in laboratory studies. Metsulfuron-methyl, chlorsulfuron, and tribenuron-methyl were 14C-labelled in the sulfonamide ring, while thifensulfuron-methyl was labelled in the thiophene ring. The highest mineralised amount in 126 days was observed for metsulfuron-methyl (40%) followed by tribenuron-methyl (25%), and thifensulfuron-methyl (11%). Chlorsulfuron showed low mineralisation in all the soils tested (<4%). Mineralisation of the herbicides metsulfuron-methyl and tribenuron-methyl varied according to soil depth (upper profile: 5-70 cm, and lower profile: 165-780 cm) and were proven faster in soil taken from depths 5-7 and 30-35 cm, and slower in depths 45-50 and 70-75 cm. Mineralisation was absent in the lower profile (165-780 cm). As an indicator of microbial activity bacterial counts were taken at the experimental start; these counts grouped in three levels: highest in the surface layer (5-7 cm), slightly lower in the depths 30-75 cm, and lowest in the lower profile (165-780 cm). Residual concentrations of metsulfuron-methyl correlated to the accumulated amount mineralised, with high residual concentrations in soil showing low mineralisation. Also chlorsulfuron showed high residual concentrations with increasing depth in the upper profile, but the relatively high dissipation at 30-35 cm and lower one at 45-50 cm could not be related with the lack of mineralisation. This shows that hydrolysis occurs, but mineralisation of the chloro-substituted sulfonamide is restricted. Tribenuron-methyl and thifensulfuron-methyl could not be detected due to interference with other compounds.     

The cockle <Emphasis Type="Italic">Cerastoderma edule</Emphasis> at Northeast Atlantic shores: genetic signatures of glacial refugia

The cockle Cerastoderma (Cardium) edule (L.) ranges from NW Africa to northern Scandinavia. Abundance in shallow coastal sediment is often high, and it attracts commercial harvest. In this study, a complex genetic pattern has been revealed by mitochondrial DNA in 383 individuals from 19 sampling sites. Parsimony network analysis of 79 haplotypes identified two dominant central haplotypes separated by low divergence. One is characteristic for a homogenous southwestern group of populations from Africa to the British Isles. The other is characteristic for a heterogeneous northern group with a deviant Arctic population. At the entrance of the Baltic Sea, a mixture zone of the dominant haplotypes was found. The estimated population expansion time for the northern haplotype group predates that of the southwestern one, suggesting northern glacial refugia and a subsequent southern expansion of C. edule populations.     

Bacterial removal and protozoan grazing in biological sand filters

The objective of the study was to investigate the importance of protozoan predation as a biological removal mechanism in sand filters used for purification of bacteria from wastewater. Eleven sand filter columns were seeded with a high dose of wastewater (70 mm d(-1)) and a high concentration (10(8) colony forming units [CFU] mL(-1)) of Aeromonas hydrophila (American Type Culture Collection [ATCC] 14715) for a period of 30 d. Water samples from three filter outlets were analyzed for the concentration of A. hydrophila. In addition, one filter column was sacrificed each sampling day for the quantification of A. hydrophila, culturable bacteria (heterotrophic plate counts, HPC), total bacterial counts, and protozoa in the sand. The mean removal efficiency of A. hydrophila in the sand filter columns was 4.7 log units. The concentration of A. hydrophila in the sand filter effluent, however, had a clearly time-dependent pattern from high (log 6) and unstable concentrations to low and more stable levels (log 2). The removal efficiency of A. hydrophila correlated significantly (P = 0.0005, r2 = 0.6) with numbers of protozoa in the sand filters. Significantly higher (P < 0.05) concentrations of A. hydrophila were observed in sand filter effluents from columns treated with the protozoan inhibitor cycloheximide, compared with nontreated columns. Results from the present study show that protozoan grazing plays an important role as a bacterial removal mechanism in sand infiltration systems.     

The dual imperative in refugee research: some methodological and ethical considerations in social science research on forced migration

Social scientists doing fieldwork in humanitarian situations often face a dual imperative: research should be both academically sound and policy relevant. We argue that much of the current research on forced migration is based on unsound methodology, and that the data and subsequent policy conclusions are often flawed or ethically suspect. This paper identifies some key methodological and ethical problems confronting social scientists studying forced migrants or their hosts. These problems include non-representativeness and bias, issues arising from working in unfamiliar contexts including translation and the use of local researchers, and ethical dilemmas including security and confidentiality issues and whether researchers are doing enough to 'do no harm'. The second part of the paper reviews the authors' own efforts to conduct research on urban refugees in Johannesburg. It concludes that while there is no single 'best practice' for refugee research, refugee studies would advance its academic and policy relevance by more seriously considering methodological and ethical concerns.