Toxic effects of thallium acetate by acute exposure to the nematode C. elegans.

BACKGROUND: Thallium (Tl) is a toxic metalloid and an emerging pollutant due to electronic devices and dispersal nearby base-metal mining. Therefore, Tl poses a threat to human health and especially the long-term impact on younger individuals exposed is still unknown. This study aimed to evaluate the toxic effects of thallium acetate in C. elegans in early larval stages, considering physiological and behavioral endpoints, as well as the Tl absorption and bioaccumulation. METHODS: Caenorhabditis elegans (C. elegans) was exposed to Thallium acetate (50, 100, 150, 200, 250, 500, and 1000 µM) in the L1 larval stage, with the purpose to observe the toxic effects invoked until adulthood. Transgenic worms strains were transported GFP, reporters to DAF-16 and were used to verify the antioxidant response. ICP-MS quantified total Tl+ concentration to evidence Tl uptake and bioaccumulation. RESULTS: Thallium acetate caused a significant reduction in the number of living worms (p < 0.0001 in 100-1000 µM), a delay in larval development (p < 0.01; p < 0.001 and p < 0.0001 in 100-1000 µM) through the larval stages, and egg production in the worm's uterus was reduced. Thallium acetate also induced behavioral changes. Additionally, thallium acetate activated antioxidant pathway responses in C. elegans by translocating the DAF-16 transcription factor and activation of SOD-3::GFP expression. The Tl+ quantification in worms showed its absorption in the L1 larval stage and bioaccumulation in the body after development. CONCLUSIONS: Thallium acetate reduced survival, delayed development, caused behavioral changes, induced responses inherent to oxidative stress, and serious damage to the worm's reproduction. In addition, C. elegans absorbed and bioaccumulated Tl+. Together, our results highlight the impacts of Tl+ exposure in the early stages of life, even for a short period.

CD4+ memory T cells are the predominant population of HIV-1-infected lymphocytes in neonates and children.

BACKGROUND: CD4+ memory T cells express CD45RO and are the principal viral reservoir in HIV-infected adults. In infants and children, CD45RO T cells comprise the minority of the CD4+ T-cell population. The majority of blood CD4+ T cells are naive, expressing CD45RA. OBJECTIVE: To determine the developmental stage at which pediatric CD4+ T cells become susceptible to HIV-1 infection in vivo by determining which T-cell population harbors HIV-1 proviral DNA. DESIGN: A prospective, cross-sectional analysis of peripheral blood CD8+ T cells, CD45RA, or CD45RO CD4+ T cells obtained from 10 HIV-infected neonates and children were analysed for provirus. METHODS: Semi-quantitative polymerase chain reaction methods were used to detect HIV-1 proviral DNA within purified lymphocyte populations selected using immunoaffinity magnetic microspheres. RESULTS: CD8+ T cells harbored no detectable HIV-1, indicating that infection of common thymocytes does not contribute to the population of infected blood T cells. In five children and two of the five neonates, the CD4+ CD45RO memory T lymphocytes contained 10-100-fold greater numbers of infected cells than the CD4+ CD45RA naive T-cell population. Three neonates, who exhibited rapid disease progression, demonstrated high proviral levels in their CD4+ CD45RA T cells. The normal age-related predominance of CD4+ CD45RA T cells was preserved independent of CD4+ T-cell attrition. CONCLUSIONS: The majority of HIV-1-infected blood CD4+ T cells in infants and children are restricted to the small population of terminally differentiated CD4+ CD45RO memory T cells. Neonates with rapid CD4+ T-cell attrition display high levels of provirus in their CD4+ CD45RA T-cell population.

Bombardier beetle based biosensor.

A biosensor constructed by combining an oxygen electrode with the liquid ejected by bombardier beetles (Pheropsophus aequinoctialis) immobolized on a collagen membrane is developed for hydrogen peroxide. The sensor presents a linear range of 2.0 x 10(-4)-2.0 x 10(-3) M and a reproductibility of approximately 2%. It shows a better lifetime than similar ones employing purified catalase. The selectivity is good since other enzymes are not present in the natural source employed.

Investigation of the use of thermometric titrimetry for the determination of acidic substances in wine.

The use of thermometric titrimetry in the determination of acidic substances in red wine is described. The titration curve obtained in the thermometric titration of red wine with strong base presents two inflections. The stoichiometry corresponding to the first inflection presents good agreement with the so-called "total acidity" of wine, and is proposed for its determination. The second inflection is related to the content of phenolic substances in red wine.

Determination of lead(II) by argentimetry.

A titrimetric method for determination of lead(II), based on the reaction between plumbite and silver ions, is described. Sodium hydroxide solution is added to the sample until the precipitate of lead hydroxide has redissolved. The solution is then made 0.025M in sodium chloride and titrated with silver nitrate. The titration is monitored with a silver electrode. An error smaller than 0.5% has been obtained for 0.05M lead (II).

Sarcoidosis in a pregnant woman.

Sarcoidosis, a rare multisystem disease, often occurs in women of childbearing age. The disease, which may be improved or exacerbated by pregnancy, presents unique considerations to the anesthesiologist. These considerations are illustrated by the case presented here of complicated sarcoidosis in a parturient who underwent cesarean section.

Development of a voltammetric method for the determination of iron(III) in Zn-Fe alloy galvanic baths.

A square wave voltammetric method with a static mercury drop electrode (SMDE) was developed for the quantitative determination of iron (III) in Zn-Fe alloy galvanic baths. Real alloy bath samples were analyzed by the standard addition method and recovery tests were carried out. 0.50 mol L-1 sodium citrate (pH 6.0) or 0.20 mol L-1 oxalic acid (pH 4.0) were applied as supporting electrolytes resulting in both cases in a peak potential of about -0.20 V vs. AgIAgCl (saturated KCl). The iron (III) concentration in the alloy bath was 9.0 x 10(-4) mol L-1. A good correlation (r = 0.9999) was achieved between the iron (III) concentration and the peak current in the electrolytes studied, with linear response ranges from 1.0 x 10(-6) to 1.2 x 10(-4) mol L-1. Interference levels for some metals such as copper (II), lead (II), chromium (III) and manganese (II) that can hinder the Zn-Fe alloy deposition were evaluated; only copper (II) interferes seriously.

Molecular analysis of highly enriched populations of T-cell-depleted monocytes.

CD4+ T lymphocytes and monocytes/macrophages are important components of the immune system. Blood monocytes are usually targeted for studies of the human macrophage lineage cells because of their accessibility through blood sampling. Most separation techniques currently available to obtain human monocytes either require large volumes of blood or do not yield a monocyte fraction sufficiently depleted of other cell types. We have developed a simple strategy to isolate a highly enriched population of monocytes from small volumes (< 6 ml) of peripheral blood by using an anti-CD14 monoclonal antibody and magnetic microspheres. Yields of monocytes ranged from 75 to 80% of CD14+ cells in peripheral blood. CD4+ T cells were subsequently selected from the monocyte-depleted peripheral blood by using an anti-CD4 monoclonal antibody and immunomagnetic beads. The effectiveness of immunomagnetic selection to yield a monocyte population highly depleted of T cells was analyzed by using a sensitive molecular strategy based on PCR amplification and detection of T-cell receptor (TCR) gene rearrangements. The relative frequency of rearranged TCRs within the monocyte population was compared with the frequency of rearranged TCRs within the CD4+ T-cell fraction from the same individual. Molecular analysis indicated that a viable monocyte population which contains fewer than 2% residual T lymphocytes can be consistently selected from small aliquots of blood.

Zidovudine administered to women infected with human immunodeficiency virus type 1 and to their neonates reduces pediatric infection independent of an effect on levels of maternal virus.

OBJECTIVE: To determine whether zidovudine, administered to reduce vertical transmission of human immunodeficiency virus type 1 (HIV-1), impacts the level of maternal viral DNA within the lymphocytes of infected pregnant women. STUDY DESIGN: A prospective, nonrandomized study of 42 HIV-1 infected pregnant women. Nineteen women received zidovudine therapy to reduce HIV-1 perinatal transmission, and 23 were untreated. HIV-1 DNA was determined by polymerase chain reaction amplification of lymphocyte DNA from maternal blood samples obtained at the time of delivery. Treated and untreated, transmitting and nontransmitting groups were compared for clinical, virologic, and immunologic parameters with at test or a Fisher Exact Test, and for copies of HIV-1 DNA per 10(6) CD4+ T cells with a Mann-Whitney rank sum test. RESULTS: Untreated pregnant women who transmitted HIV-1 to their infants had tower CD4+ T-cell counts and a greater degree of immune complex dissociated p24 antigenemia than did the untreated nontransmitting group (p < 0.01) but did not differ significantly with respect to age, race, or mode of delivery. The level of HIV-1 proviral DNA within lymphocytes was significantly greater in the untreated transmitting group than in the nontransmitting mothers (p = 0.003). Zidovudine treatment resulted in a 78% decrease in maternal transmission (p = 0.017). However, there was not a significant difference in DNA copy numbers in CD4+ T cells in the treated compared with the untreated groups. CONCLUSION: Zidovudine reduces HIV-1 maternal transmission independent of its effect on the level of the maternal peripheral blood proviral load.

Immunomagnetic selection of purified monocyte and lymphocyte populations from peripheral blood mononuclear cells following cryopreservation.

Cryopreservation is a method commonly used to store human blood samples. We sought to determine if cryopreserved peripheral blood mononuclear cells (PBMC) could be separated effectively into distinct populations by using monoclonal antibodies and immunomagnetic microspheres. PBMC obtained from healthy blood donors and from human immunodeficiency virus-infected subjects were cryopreserved for as long as 18 months. Recovered cells were separated into CD14+ monocytes and CD4+ T-cell subsets by immunomagnetic selection. Flow cytometry analysis indicated >95% depletion of monocytes from PBMC following immunomagnetic selection with anti-CD14. A highly enriched population of CD4+ T cells was obtained from the CD14-depleted cell fraction by using an anti-CD4 monoclonal antibody and detachable immunomagnetic beads. The CD4+ T cells were subsequently separated into CD4+ CD45RO and CD4+ CD45RA fractions. Each fraction contained >90% enrichment for the respective subpopulation and <5% of the reciprocal subpopulation. No significant differences in cell surface expression of leukocyte markers, in efficiency of selection of PBMC subpopulations, or in mitogen-induced proliferation were detected in freshly isolated or cryopreserved cells. Efficient recovery of cryopreserved specimens means that targeted assays can be performed on selected, prospectively stored samples once clinical endpoints have been achieved.

Determination of molybdenum in steel by adsorptive stripping voltammetry in a homogeneous ternary solvent system.

A new alternative approach for the determination of molybdenum in steel is proposed, using adsorptive stripping voltammetry (AdSV). The determinations are performed in a homogeneous ternary solvent system (HTSS) composed of N,N-dimethylformamide, ethanol and water, with alpha-benzoinoxime (alpha BO) as the complexing agent and a sodium acetate-acetic acid buffer as the support electrolyte. The HTSS composition was optimized by mixture design modelling. The AdSV measurements were performed in the differential pulse mode using an accumulation potential of -1050 mV. Under these optimized experimental conditions, the Mo(VI)-alpha BO reduction current peak potential is observed at potentials near -1250 mV, much lower than those usually reported, and the calibration plot follows the polynomial equation I = 0.359 + 0.265 [CMo(VI)] - 0.015 [CMo(IV)]2 (r2 = 0.997), for Mo concentrations up to 10.0 micrograms L-1. There is a linear range in this calibration plot for Mo(VI) concentrations up to 0.20 microgram L-1, defined by the equation I = 0.353 + 0.385 [CMo(VI)] (r2 = 0.980). In both cases, I is the absolute value for the current in microA and CMo(VI) is the concentration of Mo in microgram L-1. The detection limit for this linear concentration range was estimated as 20 pg L-1. A RSD of 0.43% is associated with the signals at a Mo(VI) level of 0.72 microgram L-1. From the common method-interfering species tested, only iron at Fe/Mo(VI) ratios above 500 and vanadium and tungsten at M/Mo(VI) ratios above 100 appear to affect the analytical response significantly. Phosphorous may also reduce the analytical signal at P/Mo(VI) ratios above 100, due to the formation of the competitive P-Mo complex. The suggested routine procedure was tested by analyzing four stainless steel samples and the results compared well with the ICP-AES measurements. The higher sensitivity of this method permits direct determination of Mo(VI) in steels, eliminating the need of analyte concentration or separation steps in the sample processing procedure.

Evaluation of the phytic acid effect on the labeling of blood elements with technetium-99m and on the survival of a strain of Escherichia coli treated with stannous fluoride.

The labeling of red blood cells with technetium-99m (99mTc) depends on a reducing agent and stannous ions, as chloride or fluoride, are widely utilized. This labeling may also be altered by drugs. Moreover, some authors have reported that the survival of Escherichia coli (E. coli) cultures decreases in presence of stannous ions. Phytic acid is present in the daily diet and we evaluated its influence on: (i) the labeling of blood elements with 99mTc and (ii) on the survival of an E. coli strain treated with stannous fluoride. Heparinized whole blood was withdrawn from Wistar rats and it was incubated with stannous chloride and with 99mTc, as sodium pertechnetate, centrifuged and plasma (P) and blood cells (BC) were isolated. Samples of P and BC were also precipitated with trichloroacetic acid, centrifuged and soluble (SF) and insoluble fractions (IF) isolated. E. coli culture was treated with stannous fluoride in presence of phytic acid. As phytic acid altered the fixation of 99mTc on BC, on IF-P and on IF-BC and, moreover, it abolished the lethal effect of stannous fluoride on the E. coli culture, we can suggest that, probably, phytic acid would have chelating properties to the stannous ions.

Implantaçäo da produçäo de 123I Ultra-puro no IEN/CNEN-RJ / Implantation of production of ultra-pure 123I in IEN/CNEN-RJ

A produção do (123)I no IEN/CNEN-RJ a partir da reação (124)TeO2(p,2n)(123)I é limitada tanto pelo seu baixa rendimento como pela sua pureza radionuclídica inviabilizando sua expedição para for a do Rio de Janeiro. Com o intuito de se vencer estas limitações é que se decidiu pela implantação da produção de (123)I ultra-puro a partir da reação (124)Xe(p,2n)(123)Cs©(123)Xe©(123)©I, método utilizado pelo FZK com quem se iniciou um intercâmbio para transferência da tecnologia dentro da nossa realidade. Com este método será possível produzir 1,0 Ci/batelada de (123)I ultra-puro.