Interindividual variation in the levels of certain urinary polycyclic aromatic hydrocarbon metabolites following medicinal exposure to coal tar ointment

Determination of human exposure to polycyclic aromatic hydrocarbons PAHs is challenging because they are so broadly distributed in the environment and often difficult to quantitate using questionnaire methods. To enhance the ability to non invasively evaluate markers of both internal dose and biologically effective dose we have developed methods for the identification and quantitation of 1 hydroxypyrene-glucuronide and r 7, t 8, t 9, c 10 tetrahydroxy 7,8,9,10 tetrahydrobenzo a pyrene BP 7,10 8,9 tetrol in human urine. In the current study we applied these assays to urine samples collected from 43 hospitalized psoriasis patients treated with coal tar medication and 39 non treated volunteer controls. BP 7,10 8,9 tetrol was detected in 20 of 43 47 patients, ranging from 1 not detected to 124 fmol mumol-1 creatinine. In contrast, BP 7,10 8,9 tetrol was detected in only 4 of 39 10 controls, range 1 to 20.6 fmol mumol-1 creatinine p = 0.0006, Wilcoxon rank sum test . A second, more polar PAH metabolite, identified as 1 hydroxypyrene-glucuronide, was present in all urine samples. Mean 1 hydroxypyreneglucuronide levels were 40.96 72.62 pmol mumol-1 creatinine in patients and 0.38 0.32 pmol mumol-1 creatinine in control subjects p 0.0001 . The ratio of urinary levels of BP 7,10 8,9 tetrol to 1 hydroxypyrene-glucuronide was examined in the coal tar treated patients. This ratio was found to vary by approximately 6000 fold. This parameter cannot be explained by measurement error because the coefficients of variation for these assays are only 12 and 10 respectively, nor can it be explained by use of different coal tar products. These results provide further evidence that substantial interindividual variation in activation of benzo a pyrene and other PAHs exists, which may have implications for disease risk.     

Mapping Topoisomerase IV Binding and Activity Sites on the E. coli Genome

Catenation links between sister chromatids are formed progressively during DNA replication and are involved in the establishment of sister chromatid cohesion. Topo IV is a bacterial type II topoisomerase involved in the removal of catenation links both behind replication forks and after replication during the final separation of sister chromosomes. We have investigated the global DNA-binding and catalytic activity of Topo IV in E. coli using genomic and molecular biology approaches. ChIP-seq revealed that Topo IV interaction with the E. coli chromosome is controlled by DNA replication. During replication, Topo IV has access to most of the genome but only selects a few hundred specific sites for its activity. Local chromatin and gene expression context influence site selection. Moreover strong DNA-binding and catalytic activities are found at the chromosome dimer resolution site, dif, located opposite the origin of replication. We reveal a physical and functional interaction between Topo IV and the XerCD recombinases acting at the dif site. This interaction is modulated by MatP, a protein involved in the organization of the Ter macrodomain. These results show that Topo IV, XerCD/dif and MatP are part of a network dedicated to the final step of chromosome management during the cell cycle.     

Separation of prostaglandins using the new horizontal flow-through coil planet centrifuge

Prostaglandins and their metabolites have been separated using the new horizontal flow-through coil planet centrifuge to perform countercurrent chromatography. The system is a continuous-flow system which provides separations similar to column and thin-layer chromatography without the use of solid supports. Either phase of a two-phase solvent system can be used to elute compounds with the low pressure produced by a metering pump. Separations were produced in PTFE tubing, 0.55 mm i.d. (wound in 0.68 cm helical diameter) with a total capacity of 24 ml. A solvent system of chloroform/acetic acid/water (2 : 2 : 1, v/v) was used at flow rates of 2.4 and 6 ml/h and at a rotation of 500 rev./min. Microgram quantities of prostaglandins E₂, F_2α, A₂, and B₂ and thromboxane B₂ can be separated. This method of can be scaled up to 260-ml columns and thromoboxane B₂ can be separated. This method can be scaled up to 260-ml columns with comparable results.     

ALK1 regulates the internalization of endoglin and the type III TGF-β receptor

Complex formation and endocytosis of transforming growth factor-β (TGF-β) receptors play important roles in signaling. However, their interdependence remained unexplored. Here, we demonstrate that ALK1, a TGF-β type I receptor prevalent in endothelial cells, forms stable complexes at the cell surface with endoglin and with type III TGF-β receptors (TβRIII). We show that ALK1 undergoes clathrin-mediated endocytosis (CME) faster than ALK5, type II TGF-β receptor (TβRII), endoglin, or TβRIII. These complexes regulate the endocytosis of the TGF-β receptors, with a major effect mediated by ALK1. Thus, ALK1 enhances the endocytosis of TβRIII and endoglin, while ALK5 and TβRII mildly enhance endoglin, but not TβRIII, internalization. Conversely, the slowly endocytosed endoglin has no effect on the endocytosis of either ALK1, ALK5, or TβRII, while TβRIII has a differential effect, slowing the internalization of ALK5 and TβRII, but not ALK1. Such effects may be relevant to signaling, as BMP9-mediated Smad1/5/8 phosphorylation is inhibited by CME blockade in endothelial cells. We propose a model that links TGF-β receptor oligomerization and endocytosis, based on which endocytosis signals are exposed/functional in specific receptor complexes. This has broad implications for signaling, implying that complex formation among various receptors regulates their surface levels and signaling intensities.     

Dysbiosis in gastrointestinal pathophysiology: Role of the gut microbiome in Gulf War Illness

Gulf War Illness (GWI) has been reported in 25%–35% of veterans returned from the Gulf war. Symptoms of GWI are varied and include both neurological and gastrointestinal symptoms as well as chronic fatigue. Development of GWI has been associated with chemical exposure particularly with exposure to pyridostigmine bromide (PB) and permethrin. Recent studies have found that the pathology of GWI is connected to changes in the gut microbiota, that is the gut dysbiosis. In studies using animal models, the exposure to PB and permethrin resulted in similar changes in the gut microbiome as these found in GW veterans with GWI. Studies using animal models have also shown that phytochemicals like curcumin are beneficial in reducing the symptoms and that the extracellular vesicles (EV) released from gut bacteria and from the intestinal epithelium can both promote diseases and suppress diseases through the intercellular communication mechanisms. The intestinal epithelium cells produce EVs and these EVs of intestinal epithelium origin are found to suppress inflammatory bowel disease severity, suggesting the benefits of utilizing EV in treatments. On the contrary, EV from the plasma of septic mice enhanced the level of proinflammatory cytokines in vitro and neutrophils and macrophages in vivo, suggesting differences in the EV depending on the types of cells they were originated and/or influences of environmental changes. These studies suggest that targeting the EV that specifically have positive influences may become a new therapeutic strategy in the treatment of veterans with GWI.     

Biodiversity as insurance: from concept to measurement and application

Biological insurance theory predicts that, in a variable environment, aggregate ecosystem properties will vary less in more diverse communities because declines in the performance or abundance of some species or phenotypes will be offset, at least partly, by smoother declines or increases in others. During the past two decades, ecology has accumulated strong evidence for the stabilising effect of biodiversity on ecosystem functioning. As biological insurance is reaching the stage of a mature theory, it is critical to revisit and clarify its conceptual foundations to guide future developments, applications and measurements. In this review, we first clarify the connections between the insurance and portfolio concepts that have been used in ecology and the economic concepts that inspired them. Doing so points to gaps and mismatches between ecology and economics that could be filled profitably by new theoretical developments and new management applications. Second, we discuss some fundamental issues in biological insurance theory that have remained unnoticed so far and that emerge from some of its recent applications. In particular, we draw a clear distinction between the two effects embedded in biological insurance theory, i.e. the effects of biodiversity on the mean and variability of ecosystem properties. This distinction allows explicit consideration of trade-offs between the mean and stability of ecosystem processes and services. We also review applications of biological insurance theory in ecosystem management. Finally, we provide a synthetic conceptual framework that unifies the various approaches across disciplines, and we suggest new ways in which biological insurance theory could be extended to address new issues in ecology and ecosystem management. Exciting future challenges include linking the effects of biodiversity on ecosystem functioning and stability, incorporating multiple functions and feedbacks, developing new approaches to partition biodiversity effects across scales, extending biological insurance theory to complex interaction networks, and developing new applications to biodiversity and ecosystem management.     

Dentin hardness differences across various mammalian taxa

Differences in dentin microstructure have been used as a tool for dietary reconstruction; however, the extent that diet is associated with this aspect of dental morphology has yet to be empirically tested. We conducted microhardness tests of mammalian dentin sections, hypothesizing that species with adaptations to particularly hard diets would have softer dentin, owing to a higher proportion of soft intertubular dentin. Species adapted to abrasive diets, in contrast, should have harder dentin, resulting from a higher proportion of hypermineralized peritubular dentin. We examined molar dentin hardness in ten mammalian taxa with durophagous diets, abrasive diets, and a comparative “control” group of mechanical generalists. Samples included six primate taxa and four non-primate species representing various dietary regimes. Our results reveal significant variation among taxa in overall hardness, but the data do not distinguish between hard and abrasive diets. Several taxa with generalized (i.e., mechanically diverse) diets resemble each other in exhibiting large variance in hardness measurements and comparably soft dentin. The high variation in these species appears to be either a functional signal supporting the niche variation hypothesis or indicate the absence of sustained unidirectional selective pressure. A possible phylogenetic signal of dentin hardness in the data also holds promise for future systematic investigations.