Effects of Methylmercury Contained in a Diet Mimicking the Wayana Amerindians Contamination through Fish Consumption: Mercury Accumulation, Metallothionein Induction, Gene Expression Variations, and Role of the Chemokine CCL2

Methylmercury (MeHg) is a potent neurotoxin, and human beings are mainly exposed to this pollutant through fish consumption. We addressed the question of whether a diet mimicking the fish consumption of Wayanas Amerindians from French Guiana could result in observable adverse effects in mice. Wayanas adult men are subjected to a mean mercurial dose of 7 g Hg/week/kg of body weight. We decided to supplement a vegetarian-based mice diet with 0.1% of lyophilized Hoplias aimara fish, which Wayanas are fond of and equivalent to the same dose as that afflicting the Wayanas Amerindians. Total mercury contents were 1.4 ± 0.2 and 5.4 ± 0.5 ng Hg/g of food pellets for the control and aimara diets, respectively. After 14 months of exposure, the body parts and tissues displaying the highest mercury concentration on a dry weight (dw) basis were hair (733 ng/g) and kidney (511 ng/g), followed by the liver (77 ng/g). Surprisingly, despite the fact that MeHg is a neurotoxic compound, the brain accumulated low levels of mercury (35 ng/g in the cortex). The metallothionein (MT) protein concentration only increased in those tissues (kidney, muscles) in which MeHg demethylation had occurred. This can be taken as a molecular sign of divalent mercurial contamination since only Hg(2+) has been reported yet to induce MT accumulation in contaminated tissues. The suppression of the synthesis of the chemokine CCL2 in the corresponding knockout (KO) mice resulted in important changes in gene expression patterns in the liver and brain. After three months of exposure to an aimara-containing diet, eight of 10 genes selected (Sdhb, Cytb, Cox1, Sod1, Sod2, Mt2, Mdr1a and Bax) were repressed in wild-type mice liver whereas none presented a differential expression in KO Ccl2(-/-) mice. In the wild-type mice brain, six of 12 genes selected (Cytb, Cox1, Sod1, Sod2, Mdr1a and Bax) presented a stimulated expression, whereas all remained at the basal level of expression in KO Ccl2(-/-) mice. In the liver of aimara-fed mice, histological alterations were observed for an accumulated mercury concentration as low as 32 ng/g, dw, and metal deposits were observed within the cytoplasm of hepatic cells.     

Electrodermal level asymmetry in a unilateral brain-damaged patient

To compare the effectiveness of various sperm preparation methods, we examined sperm concentration, percentage of progressive motility, recovery rate, and various motion characteristics in 32 semen samples after Percoll and IxaPrep preparations. Except for sperm concentration, which was much higher after IxaPrep preparation, no statistical differences existed between these two methods in terms of motile sperm concentration (MSC), recovery rate, mean curvilinear velocity (VCL), mean straight-line velocity (VSL) and mean amplitude of lateral head displacement (ALH). Among 22 samples that were allocated in a 37 degrees C, 5% CO2 incubator, the mean MSC after 3 hours was significantly higher following IxaPrep preparation than following Percoll preparation (63.2 x 10(6)/mL vs. 42.8 x 10(6)/mL, p < .03). VCL and VSL were much higher after IxaPrep preparation than after Percoll preparation, both at 3 hours (p < .01) and at 24 hours (p < .03). ALH was also higher after IxaPrep preparation than after Percoll preparation, and it was statistically significant after 3 hours of incubation (p < .03). We conclude that the IxaPrep gradient may be adopted as the preferred method to the Percoll gradient in preparing spermatozoa for assisted reproduction because of the spermatozoa's persistent and better motion activities after incubation.     

Validation of an optical surface plasmon resonance biosensor assay for screening (fluoro)quinolones in egg, fish and poultry

A surface plasmon resonance biosensor immunoassay has been developed for multi-residue determination of 13 (fluoro)quinolone antibiotics in poultry meat, eggs and fish. The following performance characteristics were determined according to the guidelines laid down for screening assay validation in European Decision 2002/657/EC: detection capability, specificity/selectivity, decision limit, repeatability, ruggedness and stability. The detection capability estimated for norfloxacin, the reference fluoroquinolone, was below 0.5, 1 and 1.5 ng g?1 for poultry meat, egg and fish, respectively. The screening assay proved specific and showed satisfactory sensitivity below the MRL levels even though flumequine and oxolinic acid had lower cross-reactivities. A wide range of non-MRL substances were also detected at concentrations below 10 ng g?1. Repeatability was good with both intra- and inter-assay coefficients of variation 56%; ruggedness was also demonstrated.     

Validation of an optical surface plasmon resonance biosensor assay for screening (fluoro)quinolones in egg,fish and poultry

A surface plasmon resonance biosensor immunoassay has been developed for multi-residue determination of 13 (fluoro)quinolone antibiotics in poultry meat, eggs and fish. The following performance characteristics were determined according to the guidelines laid down for screening assay validation in European Decision 2002/657/EC: detection capability, specificity/selectivity, decision limit, repeatability, ruggedness and stability. The detection capability estimated for norfloxacin, the reference fluoroquinolone, was below 0.5, 1 and 1.5 ng g^?1 for poultry meat, egg and fish, respectively. The screening assay proved specific and showed satisfactory sensitivity below the MRL levels even though flumequine and oxolinic acid had lower cross-reactivities. A wide range of non-MRL substances were also detected at concentrations below 10 ng g^?1. Repeatability was good with both intra- and inter-assay coefficients of variation <6%; ruggedness was also demonstrated.     

Alignment of Rod‐Shaped Single‐Photon Emitters Driven by Line Defects in Liquid Crystals

Arrays of liquid crystal defects—linear smectic dislocations—are used to trap semiconductor CdSe/CdS dot‐in‐rods which behave as single‐photon emitters. Measurements of the emission diagram are combined together with measurements of the emitted polarization of the single emitters. It is shown that the dot‐in‐rods are confined parallel to the linear defects to allow for a minimization of the disorder energy associated with the dislocation cores. It is demonstrated that the electric dipoles associated with the dot‐in‐rods, tilted with respect to the rods, remain oriented in the plane including the smectic linear defects and perpendicular to the substrate, most likely due to dipole/dipole interactions between the dipoles of the liquid crystal molecules and those of the dot‐in‐rods. Using smectic dislocations, nanorods can consequently be oriented along a unique direction for a given substrate, independently of the ligands' nature, without any induced aggregation, leading as well to a fixed azimuthal orientation for the dot‐in‐rods' dipoles. These results open the way for the fine control of nanoparticle anisotropic optical properties, in particular, fine control of single‐photon emission polarization.     

Development of a Direct Competitive Enzyme-Linked Immunosorbent Assay for the Detection of Fluoroquinolone Residues in Shrimp

Rabbit polyclonal antibodies were generated against norfloxacin, purified, and used as the basis of a direct competitive enzyme-linked immunosorbent assay for the screening of fluoroquinolones in shrimp. The developed method used a simple ethanol/acetic acid solvent extraction, which resulted in a 1.0-ng-norfloxacin/g limit of detection (based on the analysis of known negative and fortified shrimp samples). Norfloxacin extraction efficiencies were evaluated at two fortification concentrations and were greater than 70%, with an intra-assay variation less than 30%. The assay displayed greater than 10% cross reactivity against enro-, cipro-, sara-, and difloxacin. Incurred and known negative shrimp samples were analyzed and compared to the results obtained from an independent liquid chromatography tandem mass spectrometric method. All three instances in which fluoroquinolones were present at concentrations near or above the assay limit of detection (1.0 to 17 ng/g) were identified as positive by the newly developed assay, demonstrating the usefulness of this assay as a screening tool.     

Lumbar facet joint arthrography with the posterior approach

Lumbar facet joint (LFJ) arthrography with intraarticular injections of long-acting steroids and local anesthetics is routinely used for therapeutic purposes in selected patients for relief of low back pain. The procedure may also be used for diagnostic reasons to establish the source of such pain. However, because direct access to the LFJ space is not always possible owing to degenerative changes such as osteophytes, another posterior approach has been proposed for LFJ arthrography. With the patient in the prone position, a spinal needle is inserted vertically into the inferior recess of an LFJ with fluoroscopic guidance and the patient under local anesthesia. To facilitate puncture, cushions are placed under the patient's abdomen to flatten normal lumbar lordosis, which enlarges the inferior recess of the LFJ. Use of cushions also results in a decrease in tissue thickness in the patient, thereby improving image quality and decreasing radiation exposure. LFJ arthrography can demonstrate the causative role of facet disease in abnormalities responsible for low back pain or sciatica and can be performed easily and rapidly with this direct posterior approach.