A simple and rapid ultrasound-assisted extraction method with hydrochloric acid for mercury speciation in fish tissues was developed. Centrifuged extracts were directly injected into a flow injection-cold vapor atomic absorption spectrometry system. First, methylmercury was separately determined using sodium tetrahydroborate as reducing agent after selective extraction with 2 mol dm –3 hydrochloric acid. Second, inorganic mercury was determined by selective reduction with stannous chloride in 5 mol dm –3 hydrochloric acid extracts containing both mercury species. Total mercury could not be determined in the sonicated acid extracts using sodium tetrahydroborate as reducing agent because the methylmercury and inorganic mercury sensitivities were different. The detection limit was 11 and 5 ng g –1 for methylmercury and inorganic mercury, respectively. The recovery was >92% and the precision (RSD) ranged from 5 to 10% for three replicates of each sample analyzed by the standard additions method. Total mercury, calculated as the sum of methylmercury and inorganic mercury, was in agreement with the total mercury content determined after microwave digestion. The method was validated by means of three fish certified reference materials. The concentrations found were in good agreement with the certified values.
The similar circadian phases of plasminogen activator inhibitor antigen in controls and cirrhotic patients in the present investigation indicates that the output rhythm of the internal timekeeping system is not shifted in this pathological condition.
The integration of metal nanoparticles within crosslinked polymeric microgels, in a well-defined core–shell structure, offers unique possibilities in various fields due to the potential to introduce multiple functionalities by tailoring the properties of the inorganic and the organic components. This Highlight describes recent developments related to hybrid nanocomposites comprising a metal core and a smart microgel shell. Different synthesis approaches for the preparation of such hybrid systems are described, including not only surface-initiated polymerization, but also in situ chemical reactions for core optimization and functionality addition. The main properties derived from the multifunctionality of these nanocomposites are also addressed and potential applications in the fields of catalysis and sensing are presented.
A variant of the invertebrate mitochondrial genetic code was previously identified in arthropods (Abascal et al. 2006a, PLoS Biol 4:e127) in which, instead of translating the AGG codon as serine, as in other invertebrates, some arthropods translate AGG as lysine. Here, we revisit the evolution of the genetic code in arthropods taking into account that (1) the number of arthropod mitochondrial genomes sequenced has triplicated since the original findings were published; (2) the phylogeny of arthropods has been recently resolved with confidence for many groups; and (3) sophisticated probabilistic methods can be applied to analyze the evolution of the genetic code in arthropod mitochondria. According to our analyses, evolutionary shifts in the genetic code have been more common than previously inferred, with many taxonomic groups displaying two alternative codes. Ancestral character-state reconstruction using probabilistic methods confirmed that the arthropod ancestor most likely translated AGG as lysine. Point mutations at tRNA-Lys and tRNA-Ser correlated with the meaning of the AGG codon. In addition, we identified three variables (GC content, number of AGG codons, and taxonomic information) that best explain the use of each of the two alternative genetic codes.
Studies based on casual lood pressure (BP) values concluded that both age and parity have significant effects on BP during pregnancy. We have tested these results on clinically healthy normotensive women who were systematically sampled by ambulatory BP monitoring (ABPM) during their pregnancies. We analyzed 1404 BP series sampled from 234 normotensive pregnant women. BP was measured every 20 minutes during the day and every 30 minutes during the night for 48 hours with an ambulatory device once every 4 weeks from the first visit to the hospital (usually within the first trimester of gestation) until delivery. Data were divided for comparative analysis according to parity (nullipara vs multipara), age (≤25, 26-30, 31-35, and ≥35 years), and trimester of gestation. Circadian parameters established by population multiple-components analysis [Fernández & Hermida. Chronobiol Int 1998;15:191-204] were compared between groups with a nonparametric test. Effects of age and parity upon BP were also tested by ANOVA. A highly statistically significant circadian pattern described by a model that includes components with periods of 24 and 12 hours is demonstrated for systolic and diastolic BP for all groups of pregnant women in all trimesters (always P<0.001). There was no significant difference in 24-hour mean among groups divided by parity at any age or stage of pregnancy (always P>0.228). A trend of increasing BP with age was found for diastolic but not for systolic BP. Although statistically significant, differences in the 24-hour mean of diastolic BP among groups divided by age were always below 1.5 mm Hg. Data obtained from systematic ABPM in normotensive pregnant women indicate the lack of differences in BP according to parity. The small although significant increase in diastolic BP with age may have scarce influence in the proper identification of women with gestational hypertension. Reference thresholds for BP to be used in the early identification of hypertensive complications in pregnancy [Hermida et al. Hypertension 1998;31:83-89] could thus be developed as a function of rest-activity cycle and gestational age only, independently of parity or chronological age.
By far, the majority of studies in molecular evolution have focused on genetic change across one or more generations.Much less is known about the genetic changes that occur during the life time of an individual, or somatic evolution, of which cancer is probably the best-known example.Cancer is an adaptive evolutionary process in which distinct genetic clones compete for space and resources (Cairns 1975;Greaves and Maley 2012;Nowell 1976).Modern cancer biology and genomics have validated the evolutionary nature of cancer, which has attracted much attention in recent years (Burrell and Swanton 2014;Gerlinger et al. 2014).Not surprisingly, cancer genomics has unveiled a significant amount of intratumor heterogeneity in most tumor types (Burrell et al. 2013;Michor and Polyak 2010;Swanton 2012).However, but logically, most studies in cancer genomics have been mostly concerned with the identification of the genetic and epigenetic changes that lead to cell transformation, tumor growth, metastasis and drug resistance, and much less with molecular evolutionary aspects.Despite a relatively rich literature on cancer evolutionary dynamics (Michor et al. 2004;Sottoriva et al. 2011), little is known about the evolutionary mechanisms that drive tumor progression at the molecular and cellular level, and evolutionary insights in cancer are based, for the most part, on mathematical models of carcinogenesis (Beerenwinkel et al. 2015).Fortunately, the chance to obtain a more quantitative understanding of cancer molecular evolution is here.
