Determination of dialkyl phosphates in human hair for the biomonitoring of exposure to organophosphate pesticides

A new, simple, fast and sensitive method that enables the measurement of four dialkyl phosphates (DAPs) in human head hair is presented in the current study. The dialkyl phosphates, dimethyl phosphate (DMP), diethyl phosphate (DEP), diethyl thiophosphate (DETP) and diethyl dithiophosphate (DEDTP) are non-selective metabolites of the organophosphate pesticides (OPs). The extraction of DAPs from hair matrix was achieved by one step methanolic extraction. Head hair samples from general population and population occupationally exposed to OPs were analysed using gas chromatography–mass spectrometry (GC–MS) after derivatization with pentafluorobenzylbromide. The recovery of the target compounds was estimated at 84.3% for DMP, 116.1% for DEP, 109.0% for DETP and 91.5% for DEDTP. The limit of quantitation (LOQ) and detection (LOD) was 20 and 6 pg/mg for DMP, 10 and 5 pg/mg for DEP and DETP and 5 and 3 pg/mg for DEDTP, respectively. With-run and between-run precision as well as accuracy was estimated. The percentage of positive hair samples for DMP, DEP, DETP and DEDTP for the group of general population was 63.0%, 96.3%, 66.7%, and 70.4% respectively. The samples from the group with occupational exposure were positive for all dialkyl phosphates analysed. The median concentrations for DMP were 165.0 and 181.7 pg/mg, for DEP were 51.2 and 812.9 pg/mg, for DETP were 54.0 and 660.1 pg/mg, and for DEDTP were 40.0 and 60.6 pg/mg for the general population group and the group with occupational exposure respectively. Significant differences in the levels of the total dialkyl phosphates amongst exposed and not exposed groups were observed (p < 0.001). More specifically, the total ethyl phosphate (DEPs) and DAPs median concentrations were 119.5 and 301.5 pg/mg for the general population group and 1498.8 and 1694.4 pg/mg for the group with occupational exposure.     

Intragroup serotyping of meningococci

The method for obtaining antisera to meningococci of different serotypes are described and the scheme for the preparation of serotyping is presented, as well as the method for the preparation of the determinate fraction of serotype 2. Antisera to typing antigens 1, 2, 2-7, 2-10, 4, 5, 6, 8 (1) have been obtained, their specificity tested in parallel experiments with American and French typing sera. When typing meningococci, the use of antisera to purified protein antigen 2 is recommended.     

Relationship between cell density and prolidase activity in human skin fibroblasts: effects of ascorbate and fructose

To evaluate the influence of cell density on the activity of fibroblast prolidase (EC 3.4.13.9), we determined this activity in sparse and dense cultures. We also investigated, the effects of different concentrations of β-d(?) fructose and l(+) ascorbate, which both increased cell density at confluency. For a fructose concentration of 25 mM, we observed that in the absence of glucose, intracellular total proteins increased 1.5-fold and prolidase specific activity, 1.8-fold. For ascorbate, a broad optimum concentration was found (range 0.01 – 0.50 mM). Addition to cultures of 0.1 mM ascorbate increased total proteins 1.4-fold, and doubled prolidase activity. This investigation was prompted by our previous results [J. Metab. Dis. 1983, 6, 27–31], confirmed here, and suggesting that increased prolidase activity at confluency was due to a rise in cell density.     

Possible involvement of DNA breaks in epigenetic regulation of cell differentiation

The review summarizes the authors’ and literature data on accumulation of DNA breaks in differentiating cells. Large 50-kb free DNA fragments were observed by several research teams in non-apoptotic insect, mammal, and plant cells. More intense DNA breakage was observed during maturation of spermatides, embryo development, and differentiation of myotubes, epidermal cells, lymphocytes, and neutrophils. In general, accumulation of DNA breaks in differentiating cells cannot be attributed to a decrease in the DNA repair efficiency. Poly(ADP)ribose synthesis often follows the DNA breakage in differentiating cells. We hypothesize that DNA fragmentation is an epigenetic tool for regulating the differentiation process. Scarce data on localization of the differentiation-associated DNA breaks indicate their preferable accumulation in specific DNA sequences including the nuclear matrix attachment sites. The same sites are degraded at early stages of apoptosis. Recent data on non-apoptotic function of caspases provide more evidence for possible existence of a DNA breakage mechanism in differentiating cells, resembling the initial stage of apoptosis. Excision of methylated cytosine and recombination are other possible explanations of the phenomenon. Elucidation of mechanisms of differentiation-induced DNA breaks appears to be a prospective research direction.     

Cardiac myoglobin deficit has evolved repeatedly in teleost fishes

Myoglobin (Mb) is the classic vertebrate oxygen-binding protein present in aerobic striated muscles. It functions principally in oxygen delivery and provides muscle with its characteristic red colour. Members of the Antarctic icefish family (Channichthyidae) are widely thought to be extraordinary for lacking cardiac Mb expression, a fact that has been attributed to their low metabolic rate and unusual evolutionary history. Here, we report that cardiac Mb deficit, associated with pale heart colour, has evolved repeatedly during teleost evolution. This trait affects both gill- and air-breathing species from temperate to tropical habitats across a full range of salinities. Cardiac Mb deficit results from total pseudogenization in three-spined stickleback and is associated with a massive reduction in mRNA level in two species that evidently retain functional Mb. The results suggest that near or complete absence of Mb-assisted oxygen delivery to heart muscle is a common facet of teleost biodiversity, even affecting lineages with notable oxygen demands. We suggest that Mb deficit may affect how different teleost species deal with increased tissue oxygen demands arising under climate change.     

Spongelike alginate nanoparticles as a new potential system for the delivery of antisense oligonucleotides.

The aim of this study was to design a new antisense oligonucleotide (ON) carrier system based on alginate nanoparticles and to investigate its ability to protect ON from degradation in the presence of serum. Pharmacokinetics and tissue distribution of ON-loaded nanoparticles have been determined after intravenous administration. An original and dynamic process for ON loading into polymeric nanoparticles has been applied. It is based on the diffusion of ON or ON/polylysine complex into the nanoparticle or the alginate gel, respectively. Indeed, the single coincubation of ON with nanoparticles led, within a few days, to an extremely efficient association. The diffusion kinetic of ON was shown to be dependent on several parameters, incubation temperature, ON concentration, presence or absence of polylysine, polylysine molecular weight, and nanoparticle preparation procedure. This new alginate-based system was found to be able to protect [33P]-radiolabeled ON from degradation in bovine serum medium and to modify their biodistribution, as an important accumulation of radioactivity was observed in the lungs, in the liver, and in the spleen after intravenous administration into mice. ON may be associated efficiently with calcium alginate in a colloidal state. Such nanosponges are promising carriers for specific delivery of ON to lungs, liver, and spleen.     

The Expanded mtDNA Phylogeny of the Franco-Cantabrian Region Upholds the Pre-Neolithic Genetic Substrate of Basques

The European genetic landscape has been shaped by several human migrations occurred since Paleolithic times. The accumulation of archaeological records and the concordance of different lines of genetic evidence during the last two decades have triggered an interesting debate concerning the role of ancient settlers from the Franco-Cantabrian region in the postglacial resettlement of Europe. Among the Franco-Cantabrian populations, Basques are regarded as one of the oldest and more intriguing human groups of Europe. Recent data on complete mitochondrial DNA genomes focused on macrohaplogroup R0 revealed that Basques harbor some autochthonous lineages, suggesting a genetic continuity since pre-Neolithic times. However, excluding haplogroup H, the most representative lineage of macrohaplogroup R0, the majority of maternal lineages of this area remains virtually unexplored, so that further refinement of the mtDNA phylogeny based on analyses at the highest level of resolution is crucial for a better understanding of the European prehistory. We thus explored the maternal ancestry of 548 autochthonous individuals from various Franco-Cantabrian populations and sequenced 76 mitogenomes of the most representative lineages. Interestingly, we identified three mtDNA haplogroups, U5b1f, J1c5c1 and V22, that proved to be representative of Franco-Cantabria, notably of the Basque population. The seclusion and diversity of these female genetic lineages support a local origin in the Franco-Cantabrian area during the Mesolithic of southwestern Europe, ∼10,000 years before present (YBP), with signals of expansions at ∼3,500 YBP. These findings provide robust evidence of a partial genetic continuity between contemporary autochthonous populations from the Franco-Cantabrian region, specifically the Basques, and Paleolithic/Mesolithic hunter-gatherer groups. Furthermore, our results raise the current proportion (≈15%) of the Franco-Cantabrian maternal gene pool with a putative pre-Neolithic origin to ≈35%, further supporting the notion of a predominant Paleolithic genetic substrate in extant European populations.     

Mechanism of the change in erythrocyte osmotic resistance in rats exposed to valinomycin: the features seen in spontaneous hypertension

Introduction of valinomycin into erythrocyte incubation medium increased the cell stability to water-induced hemolysis. In these conditions the erythrocytes of spontaneously hypertensive and normotensive (control) rats release 63.2 +/- 1.5% and 80.9 +/- 1.6%, respectively, of the total hemoglobin content. Valinomycin effect is completely abolished with K+ substitution for Na+ and is independent of extracellular Ca2+ concentration. Valinomycin had no effect on human erythrocyte osmotic stability. It has been shown that valinomycin-induced kinetics of Na+ and K+ redistribution was different in human and rat erythrocytes. The distinctions are thought to be related to specific anion transport mediated by the third band protein--the main component of membrane cytoskeleton.