Comparison of the serum selenium content of healthy adults living in the Antwerp region (Belgium) with recent literature data.

Graphite furnace atomic absorption spectrometry, after improved matrix modification and using Zeeman background correction, was used to measure the serum selenium content of healthy adults living in the Antwerp region (Belgium). The mean serum concentration of 13 men and 13 women, sampled once a month during 1 year, was 84.3 +/- 9.4ng/ml with a broad range of 51.4-121.7 ng/ml. The intra-individual variation was remarkably high. Recent literature on selenium concentrations is reviewed and values are tabulated, with limitation to healthy adults and European countries. The mean serum selenium concentration measured corresponded well to older literature data for Belgium. The obtained values were found to be in the medium range compared with the literature data for other European countries.     

Healing the Modern in a Central Javanese City.

Healing the Modern in. Central Javanese City. Steve Ferzacca. Durham, NC: Carolina Academic Press, 2001. 280 pp.     

Introducing the Multivariate Dale Model in Population‐Based Genetic Association Studies

Until recently, the most common parametric approaches to study the combined effects of several genetic polymorphisms located within a gene or in a small genomic region are, at the genotype level, logistic regressions and at the haplotype level, haplotype analyses. An alternative modeling approach, based on the case/control principle, is to regard exposures (e.g., genetic data such as derived from Single Nucleotide Polymorphisms – SNPs) as random and disease status as fixed and to use a marginal multivariate model that accounts for inter‐relationships between exposures. One such model is the multivariate Dale model. This model is based on multiple logistic regressions. That is why the model, applied in a case/control setting, leads to straightforward interpretations that are similar to those drawn in a classical logistic modeling framework. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A new approach to polarized fluorescence using phase and modulation fluorometry

In the preceding paper, an alternative method is described for obtaining information about the reorientational behavior of a fluorophore in a membrane system from frequency domain measurements. To demonstrate this new analysis procedure, we present data for the probe-molecule 1,6-diphenyl-1,3,5-hexatriene (DPH) in l--dimyristoyl- and l--dipalmitoylphosphatidylcholine (DMPC and DPPC) obtained with two different phase fluorometers: the SLM 4800A Subnanosecond Spectrofluorometer which has only three fixed frequencies available (6, 18 and 30 MHz) and the recently constructed continuously variable multifrequency phasefluorometer (Gratton and Limkeman 1983).It will be shown that reasonable information about the anisotropy behavior of a fluorophore can be obtained even if only three frequencies are used. The phase modulation technique was also used to check the new expression for the anisotropy, r(t), called the general model and introduced by Van der Meer et al. (1984). The parameters P ₂, P ₄ and D, obtained from the nonlinear least squares fit (Bevington 1969) for this general model, confirm the results from the pulse technique of Ameloot and coworkers (Ameloot et al. 1984; Pottel et al. 1986).     

Identification and cloning of nodulation genes from the stem-nodulating bacterium ORS571

Summary After random Tn5 mutagenesis of the stem-nodulating Sesbania rostrata symbiont strain ORS571, Nif^-, Fix^- and Nod^- mutants were isolated. The Nif^- mutants had lost both free-living and symbiotic N₂ fixation capacity. The Fix^- mutants normally fixed N₂ in the free-living state but induced ineffective nodules on S. rostrata. They were defective in functions exclusively required for symbiotic N₂ fixation. A further analysis of the Nod^- mutants allowed the identification of two nod loci. A Tn5 insertion in nod locus 1 completely abolished both root and stem nodulation capacity. Root hair curling, which is an initial event in S. rostrata root nodulation, was no longer observed. A 400 bp region showing weak homology to the nodC gene of Rhizobium meliloti was located 1.5 kb away from this nod Tn5 insertion. A Tn5 insertion in nod locus 2 caused the loss of stem and root nodulation capacity but root hair curling still occurred. The physical maps of a 20.5 kb DNA region of nod locus 1 and of a 40 kb DNA region of nod locus 2 showed no overlaps. The two nod loci are not closely linked to nif locus 1, containing the structural genes for the nitrogenase complex (Elmerich et al. 1982).