A frequency comb stabilized Ti:Sa laser as a self-reference for ion-trap experiments with a 40Ca+ ion.

In this study, we report on the stabilization of a continuous-wave Ti:Sa laser to an optical frequency comb. The laser is emitting at 866 nm to address one of the transitions required for Doppler cooling of a single 40Ca+ ion in a linear Paul trap (2D3/2 ↔P1/22). The stabilized Ti:Sa laser is utilized to calibrate an ultra-accurate wavelength meter. We certify this self-reference laser source by comparing the results from monitoring the laser-cooled 40Ca+ ion in the linear Paul trap, with those obtained when a HeNe laser is used for calibration. The use of this self-reference is compatible with the simultaneous use of the comb for precision spectroscopy in the same ion-trap experiment.

The structural modeling of the interaction between levofloxacin and the Mycobacterium tuberculosis gyrase catalytic site sheds light on the mechanisms of fluoroquinolones resistant tuberculosis in Colombian clinical isolates.

We compared the prevalence of levofloxacin (LVX) resistance with that of ofloxacin (OFX) and moxifloxacin (MFX) among multidrug resistant (MDR) MTB clinical isolates collected in Medellin, Colombia, between 2004 and 2009 and aimed at unraveling the underlying molecular mechanisms that explain the correlation between QRDR-A mutations and LVX resistance phenotype. We tested 104 MDR isolates for their susceptibility to OFX, MFX, and LVX. Resistance to OFX was encountered in 10 (9.6%) of the isolates among which 8 (7.7%) were also resistant to LVX and 6 (5.7%) to MFX. Four isolates resistant to the 3 FQ were harboring the Asp94Gly substitution, whilst 2 other isolates resistant to OFX and LVX presented the Ala90Val mutation. No mutations were found in the QRDR-B region. The molecular modeling of the interaction between LVX and the DNA-DNA gyrase complex indicates that the loss of an acetyl group in the Asp94Gly mutation removes the acid base interaction with LVX necessary for the quinolone activity. The Ala90Val mutation that substitutes a methyl for an isopropyl group induces a steric modification that blocks the LVX access to the gyrase catalytic site.

Dioxins in adipose tissue of women in Southern Spain.

Seventeen polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were quantified in adipose tissue samples of non-occupationally exposed women living in Southern Spain. Geometric mean levels of sum of congeners and WHO(PCDD/F)-TEQ(2005) were 410 and 17.9pgg(-1) fat, respectively. Among PCDDs, octachlorodibenzo-p-dioxin (OCDD) showed the highest concentration with a mean value of 265pgg(-1) fat, followed by 1,2,3,6,7,8-HxCDD (49.3pgg(-1) fat) and 1,2,3,4,6,7,8-HpCDD (45.2pgg(-1) fat). These three congeners were responsible for around 90% of the sum of all PCDD/F congeners in adipose tissue. The geometric mean 2,3,7,8-TCDD value was 1.87pgg(-1) fat. 2,3,4,7,8-PeCDF (8.43pgg(-1) fat) showed the highest concentration among the PCDFs, followed by 1,2,3,4,7,8-HxCDF (4.17pgg(-1) fat) and 1,2,3,6,7,8-HxCDF (3.28pgg(-1) fat), and these three congeners were responsible for 4% of the sum of all studied PCDD/F congeners in adipose tissue and 76% of the sum of ten PCDFs. 1,2,3,7,8,9-HxCDF was the only congener not quantified in any sample, while 1,2,3,4,7,8,9-HpCDF, 1,2,3,7,8-PeCDF, OCDF and 2,3,7,8-TCDF were found in 5, 16, 16 and 19 samples, respectively. All other congeners were quantifiable in all 20 samples. Congeners contributing most to the WHO(PCDD/F)-TEQ(2005) were 1,2,3,7,8-PeCDD (31.6%), 1,2,3,6,7,8-HxCDD (28.3%) and 2,3,4,7,8-PeCDF (14.6%). The body burden of log-transformed WHO(PCDD/F)-TEQ(2005) levels increased with age (B=0.02; 95% CI=0.01, 0.03; p=0.02). Although these adipose tissue PCDD/F levels are similar to previously published findings in Spain and other European countries, further research is needed to determine trends in the exposure of women to these chemical residues.

Oestrogenicity of paper and cardboard extracts used as food containers.

Bisphenol-A (BPA), dibutyl phthalate (DBP), and di-2-ethylhexyl phthalate (DEHP), which are common chemical residues in food-packaging materials, were investigated in paper and cardboard containers used for take-away food. The oestrogenicity of aqueous extracts was tested in E-Screen bioassay and analysis carried out by high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC/MS). Oestrogenicity was demonstrated in 90% of extracts (geometric mean [GM] = 11.97 pM oestradiol equivalents g(-1)). DEHP, DBP, and BPA (GM = 341.74, 37.59, and 2.38 ng g(-1) of material) were present in 77.50, 67.50, and 47.50% of samples, respectively. In bivariate analyses, no significant association was found between the levels of these chemicals and oestrogenicity in cardboard/paper extracts. A close-to-significant association was found between oestrogenicity and DBP (beta = 1.25; p = 0.06) in paper extracts, which reached statistical significance in multivariate analysis (beta = 1.61; p = 0.03). Paper and cardboard used in food packaging may contribute to the inadvertent exposure of consumers to endocrine-disrupting chemicals.

PBDEs and PBBs in the adipose tissue of women from Spain.

Polybromodiphenyl ethers (PBDEs) and polybromobiphenyls (PBBs) were investigated in adipose tissue of women living in Southeastern Spain. Mean Sigma PBDE (BDE 28, 75, 71, 47, 66, 77, 100, 119, 99, 85, 154, 153, 138, and 183) and Sigma PBB (PBB 18, 29, 31, 22, 38, 37, 53, 52, 49, 75, 80, 56, 77, 103, 101, 155, 154, 153, and 169) levels were 3.85 and 0.36 ng/g of lipid, respectively. Among PBDEs, congeners 153, 47, 183, 99, and 100 were the most frequent and abundant and together constituted 96% of the total amount of PBDEs in adipose tissue. Concentrations of PBDEs in this population were similar to those reported in other parts of Spain and in Swedish and Belgium populations but lower than those found in other Western countries. Among PBB congeners studied, PBB 153 presented the highest concentrations and contributed 79% of all PBBs. There are no published data on PBB congeners in adipose tissues of the Spanish population for comparison, but the levels found were similar to those described in other European countries. Further research is needed to determine trends in human exposure to PBDEs and PBBs and to explore putative effects on human health.

[Perspectives on endocrine disruption]. / Perspectivas en disrupción endocrina.

Two decades ago, reports of alterations in the reproductive function of some wild animal species and clear evidence of human and animal exposure to chemical substances with hormonal activity agonist and antagonist generated what is known now as the hypothesis of endocrine disruption. This is an emerging environmental health problem that has challenged some of the paradigms on which the control and regulation of the use of chemical compounds is based. The need to include in routine toxicology tests new research objectives that specifically refer to the development and growth of species and to the homeostasis and functionality of hormonal systems, has served to complicate both the evaluation of new compounds and the re-evaluation of existing ones. The repercussions on regulation and international trade have not taken long to be felt. On both sides of the Atlantic, screening systems for endocrine disrupters have been designed and established, and research programmes have been launched to characterise and quantify adverse effects on human and animal health and to develop preventive measures.

Perspectivas en disrupción endocrina / Perspectives in endocrine disruption

La descripción de alteraciones en la función reproductora de algunas especies de animales salvajes, junto a la demostración de la exposición humana y animal a sustancias químicas con actividad hormonal -agonista y antagonista- generó, hace dos décadas, lo que se conoce hoy día como hipótesis de disrupción endocrina. Se trata de un problema emergente de salud medioambiental que ha cuestionado algunos de los paradigmas en que se fundamenta el control y la regulación de uso de los compuestos químicos. La necesidad de incluir en los tests toxicológicos habituales nuevos objetivos de investigación, que se refieren específicamente al desarrollo y crecimiento de las especies y a la homeostasis y funcionalidad de los sistemas hormonales, ha venido a complicar tanto la evaluación de los nuevos compuestos químicos como la revaluación de los existentes. Sus repercusiones sobre la reglamentación y el comercio internacional no se han hecho esperar y a ambos lados del Atlántico se han diseñado y establecido sistemas de cribado de disruptores endocrinos y se han desarrollado programas de investigación con objeto de cualificar y cuantificar los efectos adversos sobre la salud humana y animal y poder actuar con medidas de prevención (AU)