Publications

Cadmium was determined in biological materials by electrothermal atomic absorption spectrometry after ultrasound-assisted treatment of slurried samples prepared in the autosampler cups with an acidic diluent. Parameters influencing Cd extraction into the liquid phase of the slurry, such as ultrasound amplitude, sonication time, particle size, acid concentration and sample mass used for preparing the slurry, were investigated. Quantitative recoveries of Cd from mussel tissue were obtained using a 20% amplitude, a 1 min sonication time and 3% nitric acid, demonstrating that the resulting supernatant in the autosampler cup can be used for sampling. Particle size had no effect on Cd extraction from mussel tissue in the range <50 and >200 &mu;m, the recovery being quantitative. Extraction of Cd from several CRMs, such as BCR CRM 60 (Lagarosiphon major) Aquatic Plant, BCR CRM 278 Mussel Tissue, NRCC DORM-2 Dogfish Muscle and NRCC DOLT-2 Dogfish Liver, was also successful under the conditions mentioned above along with the original particle size distribution provided for these materials. Non-quantitative extraction was obtained with materials that have a typical inorganic matrix, such as BCR CRM 145R Sewage Sludge and BCR CRM 320 River Sediment. Homogeneity testing was carried out by comparison of between- and within-batch precision as well as homogeneity factors. The LOD for Cd in the solid biological samples was 0.019 &mu;g g –1 when a 10 mg sample mass was slurried in a volume of 1.5 ml. In all cases, an acceptable homogeneity was observed even when using a sample mass of 10 mg for slurry preparation. In addition, the proposed approach for analyte extraction should provide further advantages in comparison with conventional slurry sampling, such as an improved precision, since the representative sub-sample is the whole mass taken for slurry preparation, lower background signals and a decreased build-up of carbonaceous residues inside the graphite tube.

The cross-sectional 24h ambulatory blood pressure (BP) monitoring (ABPM) study by de la Sierra et al. reported 37.5% incidence of isolated-office (“white-coat“) resistant hypertension (RH), defined as clinic BP ≥140/90 mmHg plus 24h BP mean &lt;130/80 mmHg; it was even higher (44.1%) when defined by daytime BP mean &lt;135/85 mmHg. This is markedly higher than the 17.4% estimate based on more reproducible 48h ABPM and defined as clinic BP ≥140/90 mmHg plus daytime and nighttime BP means of &lt;135/85 mmHg and &lt;120/70 mmHg, respectively. The findings of de la Sierra et al. might well be an overestimation, because: (i) among patients defined as “white-coat RH”, 34.4% ingested ≥4 hypertension medications/daily; by definition, treatment with &gt;3 medications/daily is true RH, regardless of BP values; accordingly, inclusion of RH patients treated with ≥4 medications would decrease the prevalence of white-coat RH to 24.6%; (ii) RH is characterized by high prevalence of nocturnal hypertension and abnormal non-dipper BP pattern; current guidelines designate separate diagnostic thresholds for daytime and nighttime ABPM means; mean nighttime BP ≥120/70 mmHg should be considered hypertensive, regardless of mean daytime or clinic BP. The investigator-promoted, government-funded Hygia Project, designed to prospectively evaluate cardiovascular disease (CVD) risk in primary care centers of Northwest Spain using highly reproducible 48h ABPM, substantiates elevated sleep-time BP is highly prevalent in diabetes, chronic kidney disease, and RH, and significantly more frequent than elevated daytime BP. Furthermore, prevalence of isolated-office hypertension was up to three times higher when defined only by the daytime BP mean, than jointly by the daytime and nighttime BP means. Despite current recommendations, use of the 24h BP mean to diagnose isolated-office hypertension, as done by de la Sierra et al., is inadequate; a “normal” 24h BP mean is not a guarantee of a normal nighttime BP mean. Subjects with the same 24h BP mean might have a BP pattern ranging from extreme-dipping to rising (asleep BP mean &gt; awake BP mean), with potentially markedly different CVD risk. Elevated sleep-time BP is a better predictor of CVD risk than awake or 24h BP means, and treatment-induced reduction of sleep-time BP in hypertension has been prospectively shown to be the most significant independent predictor of event-free survival. In conclusion, de la Sierra et al. cannot challenge findings from randomized, prospective clinical trials consistently reporting that bedtime ingestion of hypertension medications improves BP control and increases CVD event-free survival of RH patients.

Adsorption of dissolved organic matter (DOM) to two species of marine phytoplankton (Isochrysis galbana and Thalassiosira weissflogii) was evaluated and quantified, and effects of DOM on the growth rate and Pb bioavailability were tested for I. galbana and compared with T. weissflogii. Isochrysis galbana growth rate was stimulated by different types of DOM. Humic acids (HA) had the highest stimulatory effect on cell growth followed by Suwannee river dissolved organic matter (SRDOM) and fulvic acids (FA). DOM also enhanced Pb adsorption and internalization by I. galbana, and the magnitude of these effects followed the same order: HA > SRDOM—FA, which was also the same order observed for the magnitude of DOM adsorption to surfaces. It is hypothesized that DOM adsorption on membrane surfaces may be a necessary step to cause both the increase in growth rate and the increase in Pb internalization by the algae, effects not observed in the case of the diatom T. weissflogii, an organism with an outer silica wall, thought to be the primary site of DOM adsorption. The different degree of effects caused by the different types of DOM may be explained according to their physicochemical properties.

Using in silico amplified fragment length polymorphism (AFLP) fingerprints, we explore the relationship between sequence similarity and phylogeny accuracy to test when, in terms of genetic divergence, the quality of AFLP data becomes too low to be informative for a reliable phylogenetic reconstruction. We generated DNA sequences with known phylogenies using balanced and unbalanced trees with recent, uniform and ancient radiations, and average branch lengths (from the most internal node to the tip) ranging from 0.02 to 0.4 substitutions per site. The resulting sequences were used to emulate the AFLP procedure. Trees were estimated by maximum parsimony (MP), neighbor-joining (NJ), and minimum evolution (ME) methods from both DNA sequences and virtual AFLP fingerprints. The estimated trees were compared with the reference trees using a score that measures overall differences in both topology and relative branch length. As expected, the accuracy of AFLP-based phylogenies decreased dramatically in the more divergent data sets. Above a divergence of approximately 0.05, AFLP-based phylogenies were largely inaccurate irrespective of the distinct topology, radiation model, or phylogenetic method used. This value represents an upper bound of expected tree accuracy for data sets with a simple divergence history; AFLP data sets with a similar divergence but with unbalanced topologies and short ancestral branches produced much less accurate trees. The lack of homology of AFLP bands quickly increases with divergence and reaches its maximum value (100%) at a divergence of only 0.4. Low guanine-cytosine (GC) contents increase the number of nonhomologous bands in AFLP data sets and lead to less reliable trees. However, the effect of the lack of band homology on tree accuracy is surprisingly small relative to the negative impact due to the low information content of AFLP characters. Tree-building methods based on genetic distance displayed similar trends and outperformed parsimony at low but not at high divergences. However, the impact of using alternative phylogenetic methods on tree accuracy was generally small relative to the uncertainty arising from factors such as divergence, nonhomology of bands, or the low information content of AFLP characters. Nevertheless, our data suggest that under certain circumstances, AFLPs may be suitable to reconstruct deeper phylogenies than usually accepted.

Polycyclic Aromatic Hydrocarbons (PAHs) are environmental carcinogens which are produced in food during their processing and thermal treatment. Consumption of such foods results in diverse diseases including cancer in humans, raising a serious need to either prevent formation of these compounds in food or reduce and remove these carcinogens once they are formed. The concern is very important and reasonable as diet contributes to 88–98% exposure. Some of the processes followed to prevent PAHs formation include regulation of the cooking/processing practices/methods and revolves around deodorization and refining of oil as well as sugars, choosing right type of oil and frying process, choosing liquid smoking process over traditional practices, reducing fat content of product and preferring the right part of product (especially in meats), roasting and baking products at lower time-temperature combinations with preferences to electric oven and indirect processes, using the right heat medium (wood chips for barbequeing/charcoal grilling, using correct wraps for food products to prevent direct contact with heat and fat drippings and much more. Though these processes may be followed at household and commercial scales and have been stated in several published literature, but the absence of PAHs may not always be guaranteed in food products. This leaves the scientific community to attempt and develop strategies which can remove the already existing PAHs from food products and needs to be extensively reviewed and worked in future. This review bridges the PAHs’ reduction and removal strategies [different types of ingredients (marination, spice addition), the specific kind of packaging (aluminium foils, plastic films, charred barrels, paraffin rind), the heating treatments (irradiation, microwave preheating, defatting, brewing etc.), but also the characteristics of adsorbents and filters used (active charcoal, diatomaceous earth, zeolite filters, molecular sieves), together with innovative removal apparatus] with emphasis on biological and physical-chemical factors influencing their formation/reduction or removal/degradation, mainly in heat-processed food [such as composition and surface adsorption properties, etc.]. The overall goal is to develop the understanding of the interactions amongst all factors affecting PAHs removal and draw recommendations based on conclusions of scientific evidence and propose future challenges in this area.