Children with Amalgam Dental Restorations Have Significantly Elevated Blood and Urine Mercury Levels.

Human exposure to organic mercury (Hg) as methylmercury (MeHg) from seafood consumption is widely considered a health risk because pure methylmercury is extremely neurotoxic. In contrast, the clinical significance of Hg exposure from amalgam (AMG) dental restorations, the only other major nonoccupational source of Hg exposure, has long been debated. Here, we examined data from the two most recent National Health and Nutrition Examination Surveys (NHANES) on 14 181 subjects to assess the contributions of seafood consumption versus AMG to blood total mercury (THg), inorganic mercury (IHg), and methyl mercury (MeHg) and to urine creatinine corrected mercury (UTHg).

Correction to: Transcriptional responses of Escherichia coli during recovery from inorganic or organic mercury exposure.

After publication of the original article [1] the authors noted that the key displayed in Figure 1a was incorrect, as the PMA and HgCl2 conditions had been switched.

Transcriptional responses of Escherichia coli during recovery from inorganic or organic mercury exposure.

Background: The protean chemical properties of mercury have long made it attractive for diverse applications, but its toxicity requires great care in its use, disposal, and recycling. Mercury occurs in multiple chemical forms, and the molecular basis for the distinct toxicity of its various forms is only partly understood. Global transcriptomics applied over time can reveal how a cell recognizes a toxicant and what cellular subsystems it marshals to repair and recover from the damage.

Organic and inorganic mercurials have distinct effects on cellular thiols, metal homeostasis, and Fe-binding proteins in Escherichia coli.

The protean chemical properties of the toxic metal mercury (Hg) have made it attractive in diverse applications since antiquity. However, growing public concern has led to an international agreement to decrease its impact on health and the environment. During a recent proteomics study of acute Hg exposure in E.

Large plasmids of Escherichia coli and Salmonella encode highly diverse arrays of accessory genes on common replicon families.

Plasmids are important in evolution and adaptation of host bacteria, yet we lack a comprehensive picture of their own natural variation. We used replicon typing and RFLP analysis to assess diversity and distribution of plasmids in the ECOR, SARA, SARB and SARC reference collections of Escherichia coli and Salmonella. Plasmids, especially large (≥30 kb) plasmids, are abundant in these collections.

Regulation of the integrase and cassette promoters of the class 1 integron by nucleoid-associated proteins.

The integrase IntI1 catalyses recombination of antibiotic-resistance gene cassettes in the integron, a widely found bacterial mobile element active in spreading antibiotic multi-resistance. We have previously shown that resistance cassette recombination rate and specificity depend on the amount of intracellular integrase. Here, we used in vivo and in vitro methods to examine convergent expression of the integrase promoter (P(int)) and of the cassette promoters (P(c) and P(2)) in the prototypical plasmid-borne class 1 integron, In2.

Discovering mercury protein modifications in whole proteomes using natural isotope distributions observed in liquid chromatography-tandem mass spectrometry.

The identification of peptides that result from post-translational modifications is critical for understanding normal pathways of cellular regulation as well as identifying damage from, or exposures to xenobiotics, i.e. the exposome.

Euchromatic 9q13-q21 duplication variants are tandem segmental amplifications of sequence reciprocal to 9q13-q21 deletions.

Background: There are four known pericentromeric euchromatic variants of chromosome 9 in the literature that are increasingly being observed in diagnostic cytogenetic laboratories. These variants pose diagnostic and counselling dilemmas, especially in prenatal settings, as distinction of a pathogenic alteration from a euchromatic variant is difficult. The molecular characterisation of three of these four variants has been reported.

Prospective validation of quantitative fluorescent polymerase chain reaction for rapid detection of common aneuploidies.

Purpose: To prospectively validate a quantitative fluorescent polymerase chain reaction (PCR) assay as a method of rapid prenatal aneuploidy detection for chromosomes 13, 18, 21, X, and Y.

Methods: A commercial quantitative fluorescent PCR kit was validated on 200 known, blinded, prenatal DNA specimens. The kit was then validated prospectively on 1069 amniotic fluid specimens, and the results were compared with the karyotype results and the results of interphase fluorescence in situ hybridization testing, when performed in the course of standard care.

Supramolecular dendrimer capsules by cooperative binding.

We exploit the unique features of dendrimers as molecular nanospheres with many peripheral binding sites to show that maximizing cooperative binding enables a novel modular self-assembly approach to construct supramolecular capsules.

Emergence of resistance among USA300 methicillin-resistant Staphylococcus aureus isolates causing invasive disease in the United States.

USA300 methicillin-resistant Staphylococcus aureus (MRSA) isolates are usually resistant only to oxacillin, erythromycin, and, increasingly, levofloxacin. Of these, oxacillin and levofloxacin resistances are chromosomally encoded. Plasmid-mediated clindamycin, mupirocin, and/or tetracycline resistance has been observed among USA300 isolates, but these descriptions were limited to specific patient populations or isolated occurrences.

Structure and conformational dynamics of the metalloregulator MerR upon binding of Hg(II).

The bacterial metalloregulator MerR is the index case of an eponymous family of regulatory proteins, which controls the transcription of a set of genes (the mer operon) conferring mercury resistance in many bacteria. Homodimeric MerR represses transcription in the absence of mercury and activates transcription upon Hg(II) binding. Here, the average structures of the apo and Hg(II)-bound forms of MerR in aqueous solution are examined using small-angle X-ray scattering, indicating an extended conformation of the metal-bound protein and revealing the existence of a novel compact conformation in the absence of Hg(II).

Genetic education for primary care providers: improving attitudes, knowledge, and confidence.

Objective: To increase primary care providers' awareness and use of genetic services; increase their knowledge of genetic issues; increase their confidence in core genetic competencies; change their attitudes toward genetic testing for hereditary diseases; and increase their confidence as primary care genetic resources.

Design: Participants completed a workshop and 3 questionnaires: a baseline questionnaire, a survey that provided immediate feedback on the workshop itself, and a follow-up questionnaire 6 months later.

Setting: Ontario.

Mechanism of Hg-C protonolysis in the organomercurial lyase MerB.

Demethylation is a key reaction in global mercury cycling. The bacterial organomercurial lyase, MerB, catalyzes the demethylation of a wide range of organomercurials via Hg-C protonolysis. Two strictly conserved cysteine residues in the active site are required for catalysis, but the source of the catalytic proton and the detailed reaction mechanism have not been determined.

Damage control: regulating defenses against toxic metals and metalloids.

Some elements are essential for life and others closely related to them are very toxic. In exploiting unique ecological niches many prokaryotes have evolved the means to defend themselves against and even to derive energy from deleterious elements. Toxic metal defense systems are related to those providing homeostasis of essential metals and metalloid elements.

Cornelia de Lange syndrome (CdLS): prenatal and autopsy findings.

Cornelia de Lange Syndrome (CdLS) is a multisystem disorder characterized by somatic defects and mental retardation. Prenatal diagnosis of this severe condition is difficult in view of the non-specific ultrasound abnormalities. We report three cases with prenatally suspected CdLS based on the ultrasound findings as well as low PAPP-A detected on first trimester screening in one case, and the results of the autopsy and the NIPBL gene mutation analysis.

Intracellular steady-state concentration of integron recombination products varies with integrase level and growth phase.

IntI1 mediates the recombination of antibiotic-resistant gene cassettes between different integrons in the same cell, facilitating the persistence and dissemination of these genes. Historically, integrase activity has been measured by conjugating recombinant products from donor cells overexpressing integrase and quantifying them in recipient cells. Here we report the first measurements of the steady-state intracellular abundance of integrase-mediated recombination products in strains expressing natural or high IntI1 levels.

Recurrent reciprocal 1q21.1 deletions and duplications associated with microcephaly or macrocephaly and developmental and behavioral abnormalities.

Chromosome region 1q21.1 contains extensive and complex low-copy repeats, and copy number variants (CNVs) in this region have recently been reported in association with congenital heart defects, developmental delay, schizophrenia and related psychoses. We describe 21 probands with the 1q21.

Prospective experience with integrated prenatal screening and first trimester combined screening for trisomy 21 in a large Canadian urban center.

Objectives: To evaluate the performance of integrated prenatal screening (IPS) and first trimester combined screening (FTS) for trisomy 21 in a large Canadian urban center.

Method: Prospective data collection on women having FTS at one center from 1 November 2003 to 31 December 2005, or IPS at another from 1 January 2003 to 31 December 2005. A positive screen was defined as adjusted risk for trisomy 21 >or= 1/200 at term or nuchal translucency >or= 3.