RESUMO
Background: Lead is a neurotoxic metal potentially affecting the developing brain. Children are particularly susceptible since they can absorb between 50% and 100% of ingested lead. There is no safe level for lead, therefore preventing exposure is crucial. We previously reported a positive association between lead concentrations found in candy and concurrent blood lead levels in Mexican children. This first report garnered media and the general public's attention. Objective: To conduct a follow-up study to assess lead concentrations in candy brands that we previously reported with concentrations ≥0.1ppm the U.S. Food and Drug Administration's recommended maximum lead level in candy likely to be consumed frequently by small children. Methods: In 2018 we analyzed 50 additional candy samples. Lead concentrations were analyzed by an inductively coupled plasma mass spectrometer and lead content per candy unit was calculated. Findings: We found concentrations were typically low, with a marked decrease from prior levels (2008). Nevertheless two candy units had concentrations of 0.1 ppm of lead. Conclusions: Candy may have lead concentrations up to 0.1 ppm and 1.2 µg per unit. This is a concern because candies are exported and consumed in many countries worldwide potentially resulting in human exposure. Continued public health surveillance is needed to protect populations especially vulnerable to lead exposure, especially children.
Assuntos
Doces/análise , Contaminação de Alimentos/análise , Intoxicação por Chumbo/prevenção & controle , Chumbo/análise , Política Pública , Contaminação de Alimentos/legislação & jurisprudência , Contaminação de Alimentos/prevenção & controle , Humanos , México , Espectrofotometria AtômicaRESUMO
BACKGROUND: The programming of sleep architecture begins in pregnancy and depends upon optimal in utero formation and maturation of the neural connectivity of the brain. Particulate air pollution exposure can disrupt fetal brain development but associations between fine particulate matter (PM2.5) exposure during pregnancy and child sleep outcomes have not been previously explored. METHODS: Analyses included 397 mother-child pairs enrolled in a pregnancy cohort in Mexico City. Daily ambient prenatal PM2.5 exposure was estimated using a validated satellite-based spatio-temporally resolved prediction model. Child sleep periods were estimated objectively using wrist-worn, continuous actigraphy over a 1-week period at age 4-5â¯years. Data-driven advanced statistical methods (distributed lag models (DLMs)) were employed to identify sensitive windows whereby PM2.5 exposure during gestation was significantly associated with changes in sleep duration or efficiency. Models were adjusted for maternal education, season, child's age, sex, and BMI z-score. RESULTS: Mother's average age was 27.7â¯years, with 59% having at least a high school education. Children slept an average of 7.7â¯h at night, with mean 80.1% efficiency. The adjusted DLM identified windows of PM2.5 exposure between 31 and 35â¯weeks gestation that were significantly associated with decreased sleep duration in children. In addition, increased PM2.5 during weeks 1-8 was associated with decreased sleep efficiency. In other exposure windows (weeks 39-40), PM2.5 was associated with increased sleep duration. CONCLUSION: Prenatal PM2.5 exposure is associated with altered sleep in preschool-aged children in Mexico City. Pollutant exposure during sensitive windows of pregnancy may have critical influence upon sleep programming.
Assuntos
Exposição Ambiental , Exposição Materna , Material Particulado/toxicidade , Transtornos do Sono-Vigília/etiologia , Adulto , Pré-Escolar , Estudos de Coortes , Feminino , Desenvolvimento Fetal , Humanos , Masculino , México , Material Particulado/análise , Gravidez , Estações do AnoRESUMO
We have performed a systematic mutagenesis of three hydrophobic rings (17', 13' and 9') within transmembrane region (TM) 2 of the alpha9alpha10 nicotinic cholinergic receptor (nAChR) to a hydrophilic (threonine) residue and compared the properties of mutant receptors reconstituted in Xenopus laevis oocytes. Phenotypic changes in alpha9alpha10 mutant receptors were evidenced by a decrease in the desensitization rate, an increase in both the EC(50) for ACh as well as the efficacy of partial agonists and the reduction of the allosteric modulation by extracellular Ca(2+). Mutated receptors exhibited spontaneous openings and, at the single-channel level, an increased apparent mean open time with no major changes in channel conductance, thus suggesting an increase in gating of the channel as the underlying mechanism. Overall, the degrees of the phenotypes of mutant receptors were more overt in the case of the centrally located V13'T mutant. Based on the atomic model of the pore of the electric organ of the Torpedo ray, we can propose that the interactions of side chains at positions 13' and 9' are key ones in creating an energetic barrier to ion permeation. In spite of the fact that the roles of the TM2 residues are mostly conserved in the distant alpha9alpha10 member of the nAChR family, their mechanistic contributions to channel gating show significant differences when compared to other nAChRs. These differences might be originated from slight differential intramolecular rearrangements during gating for the different receptors and might lead each nAChR to be in tune with their physiological roles.
Assuntos
Ativação do Canal Iônico/genética , Subunidades Proteicas/genética , Receptores Nicotínicos/genética , Acetilcolina/farmacologia , Regulação Alostérica , Sequência de Aminoácidos , Animais , Cálcio/farmacologia , Colinérgicos/farmacologia , Relação Dose-Resposta a Droga , Potenciais da Membrana/efeitos dos fármacos , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Oócitos/metabolismo , Técnicas de Patch-Clamp , Fenótipo , Subunidades Proteicas/química , Subunidades Proteicas/metabolismo , Receptores Nicotínicos/química , Receptores Nicotínicos/metabolismo , Proteínas Recombinantes/metabolismo , Alinhamento de Sequência , Transfecção , Xenopus laevisRESUMO
BACKGROUND: Tetracyclines have been extensively used as adjunctives to conventional periodontal therapy. Emergence of resistant strains, however, has been reported. This study evaluated longitudinally the tetracycline resistance patterns of the subgingival microbiota of periodontitis subjects treated with systemic or local tetracycline therapy+scaling and root planing (SRP). METHODS: Thirty chronic periodontitis patients were randomly assigned to three groups: SRP+500 mg of systemic tetracycline twice/day for 14 days; SRP alone and SRP+tetracycline fibers (Actsite) at four selected sites for 10 days. Subgingival plaque samples were obtained from four sites with probing pocket depths (PPD)> or =6 mm in each patient at baseline, 1 week, 3, 6 and 12 months post-therapy. Samples were dispersed and diluted in pre-reduced anaerobically sterilized Ringer's solution, plated on Trypticase Soy Agar (TSA)+5% blood with or without 4 microg/ml of tetracycline and incubated anaerobically for 10 days. The percentage of resistant microorganisms were determined and the isolates identified by DNA probes and the checkerboard method. Significance of differences among and within groups over time was sought using the Kruskal-Wallis and Friedman tests, respectively. RESULTS: The percentage of resistant microorganisms increased significantly at 1 week in the tetracycline groups, but dropped to baseline levels over time. The SRP+Actsite group presented the lowest proportions of resistant species at 6 and 12 months. No significant changes were observed in the SRP group. The predominant tetracycline-resistant species included Streptococcus spp., Veillonela parvula, Peptostreptococcus micros, Prevotella intermedia, Gemella morbillorum and Actinobacillus actinomycetemcomitans (Aa). A high percentage of sites with resistant Aa, Porphyromonas gingivalis and Tanerella forsythensis was observed in all groups at baseline. However, T. forsythensis was not detected in any group and P. gingivalis was not present in the SRP+Actsite group at 1 year post-therapy. Aa was still frequently detected in all groups after therapy. However, the greatest reduction was observed in the SRP+Actsite group. CONCLUSION: Local or systemically administered tetracycline results in transitory selection of subgingival species intrinsically resistant to this drug. Although the percentage of sites harboring periodontal pathogens resistant to tetracycline were quite elevated in this population, both therapies were effective in reducing their prevalence over time.
Assuntos
Antibacterianos/uso terapêutico , Periodontite/microbiologia , Resistência a Tetraciclina , Tetraciclina/uso terapêutico , Aggregatibacter actinomycetemcomitans/efeitos dos fármacos , Antibacterianos/administração & dosagem , Bacteroides/efeitos dos fármacos , Celulose/administração & dosagem , Placa Dentária/microbiologia , Raspagem Dentária , Sistemas de Liberação de Medicamentos , Feminino , Seguimentos , Humanos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Peptostreptococcus/efeitos dos fármacos , Bolsa Periodontal/tratamento farmacológico , Bolsa Periodontal/microbiologia , Periodontite/tratamento farmacológico , Porphyromonas gingivalis/efeitos dos fármacos , Prevotella intermedia/efeitos dos fármacos , Aplainamento Radicular , Streptococcus/efeitos dos fármacos , Tetraciclina/administração & dosagem , Veillonella/efeitos dos fármacosRESUMO
Dados de prevalencia e incidencia da esquistossomose foram estimados, acompanhando-se um grupo de escolares residentes em area rural do municipio de Itariri (Sao Paulo, Brasil), por um periodo de 2 anos, com cinco inqueritos, um a cada semestre, realizados no primeiro semestre de cada ano entre marco e abril e no segundo, entre setembro e outubro. O hospedeiro intermediario do Schistosoma mansoni na area e a Biomphalaria tenagophila. A infeccao pelo S. mansoni foi determinada pelo metodo parasitologico de Kato-Katz, atraves do exame de tres laminas, e os resultados analisados comparativamente aos da reacao de imunofluorescencia para deteccao de anticorpos IgM (RIF-IgM). Foram encontrados nos cinco inqueritos indices de prevalencia de 8,6 por cento, 6,8 por cento, 9,9 por cento, 5,8 por cento e 17,2 por cento pelo metodo parasitologico...