Long-term exposure to environmentally relevant doses of methyl-tert-butyl ether causes significant reproductive dysfunction in the zebrafish (Danio rerio)

Methyl-tert-butyl ether (MTBE), an anthropogenic chemical used as a gasoline additive, is being detected at an increasing frequency in the environment. The acute lethal concentration that kills 50% of the fish test population and the chronic effects of exposure to MTBE were investigated in the zebrafish (Danio rerio). Chronic exposure over three weeks to effective MTBE conceritrations as low as 0.11 mg/L induced a significant increase in the vitellogenin concentration of male fish. The impact of a chronic, eight-week exposure at effective concentrations ranging from 0.44 to 220 mg/L had no significant effect on fecundity, fertilization, or hatch rate but highly significant impacts on sperm motility. Spermatozoa of all MTBE-exposure groups showed a significantly lower straight-line velocity and lower average path velocity compared to those of the nonexposed group. These results suggest that chronic exposure to MTBE negatively affects fish sperm motility at concentrations that are environmentally relevant and several orders of magnitude lower than concentrations inducing acute effects.     

Nanotechnology in bio/clinical analysis

Nanotechnology is being exploited now in different fields of analytical chemistry: Single cell analysis; in chip/micro machined devices; hyphenated technology and sampling techniques. Secretory vesicles can be chemically and individually analyzed with a combination of optical trapping, capillary electrophoresis separation, and laser induced fluorescence detection. Attoliters (10(-18) l) can be introduced into the tapered inlets of separation capillaries. Chip technology has come of age in the field of genomics, allowing faster analyses, and will fulfil an important role in RNA and peptide/protein analysis. The introduction of nanotechnology in LC-MS and CE-MS has resulted in new findings in the study of DNA adduct formation caused by carcinogenic substances, including anticancer drugs. Sample handling and introduction also can benefit from nanotechnology: The downscaling of sample volumes to the picoliter level has resulted in zeptomole (10(-21)) detection limits in the single-shot mass spectrum of proteins.     

Comparison of Actical and activPAL measures of sedentary behaviour in preschool children

ObjectivesThe purpose of this study was to examine the convergent validity of the Actical and activPAL to measure sedentary behaviour (SB) and non-SB in preschoolers in a free-living environment.DesignA convenience sample of 49 preschoolers (22 boys; 4.0 ± 0.5 years) from six early childhood centres in Auckland, New Zealand were included in data analysis.MethodsParticipants wore a hip-mounted Actical and a thigh-mounted activPAL accelerometer simultaneously during centre attendance for one day and data were collected in 15 s epochs. Bland–Altman tests were used to assess differences in group mean minutes and percentage of time in (non-)SB between both monitors. Agreement between binary coded (SB vs. non-SB) 15 s-by-15 s Actical and activPAL data was evaluated by calculating percentage agreement and κ statistic.ResultsThe monitors were worn on average for 294.8 ± 46.3 min resulting in a total of 57,780 15 s epochs. Bland–Altman tests suggested a small group mean difference in (non-)SB (1.3 min; 0.1%) and a wide prediction interval (121.3 min; 39.2%). No obvious systematic bias was observed in the Bland–Altman plot. Percentage agreement between the 15 s-by-15 s Actical and activPAL data of all participants was 73.0% (inter-child range: 36.8–93.8%). The κ statistic showed moderate agreement with a value of 0.46 (95% CI: 0.45–0.47).ConclusionsAlthough the group mean estimate of (non-)SB was similar between the Actical and activPAL, the output of both monitors cannot be considered convergent as meaningful random disagreement was found between both monitors.     

Validity of parentally reported versus measured weight,length and waist in 7- to 9-year-old children for use in follow-up studies

The aim of this prospective cohort study was to assess the validity of parentally reported anthropometric data compared to measured data in 7- to 9-year-old Flemish children especially for use in follow-up studies. The subjects were 116 Flemish children of a birth cohort recruited in the first Flemish Environment and Health Study (2002–2003). Data about anthropometric measures (waist circumference (WC), weight and length) were obtained by a postal parentally reported questionnaire and during a home visit. Our study showed that parents tend to overreport their child’s WC and underreport the BMI, especially in children with large WC and high BMI. The median difference between measured and parentally reported WC was 1.6 % of the median measured WC; for BMI, the median difference was 2.8 % of the median measured BMI. Both for WC and BMI, we observed a good agreement between parentally reported values and measured values to classify children in the highest 10 and 20 % of the study population. When classifying the children in ‘overweight’ and ‘not overweight’, there were less misclassifications when parentally reported WC was used compared to parentally reported BMI. Conclusions: Although there is a high agreement between parentally reported and measured WC, the parentally reported data must be used with reserve. Moreover, this study is the first to suggest that WC is a better indicator compared to BMI when parentally reported values are used to classify children.     

A quantitative genetic study of cephalometric variables in twins

This study aimed at determining the relative genetic and environmental impact on a number of well-known cephalometric variables in twins. In order to find a clue in the heritability pattern of some dentofacial characteristics and on the expected limits of the therapeutic impact on the dentofacial subparts they are representing. Cephalograms were collected from 33 monozygotic and 46 dizygotic twins, who did not undergo any orthodontic treatment. Nineteen linear and four angular variables were selected all representing a different definite subpart of the dentofacial complex. The reproducibility of the measurement of most of the linear variables was very high. A genetic analysis using model fitting and path analysis was carried out. First, data were checked on the fulfilment of the conditions for genetic analysis in twins reared together. The results show that the genetic determination is significantly higher for vertical (72%) than for horizontal (61%) variables. As far as the genetic component is concerned, all variables selected seem to be inherited by additive genes, except for mandibular body length, which was determined by dominant alleles. Sex differences in genetic determination were found for the anterior face height, showing a significantly higher genetic component for boys (91%) than for girls (68%). For the angular measurements, no genetic influence was found: only environmental influences common to both members of each pair could be demonstrated.