RESUMO
Prenatal exposure to polychlorinated biphenyls (PCBs) was examined by analysis of cord tissue from 435 children from a Faroese birth cohort. Analysis of 50 paired cord blood samples showed excellent correlation with the cord tissue concentration (r=.90). Among 17 neuropsychological outcomes determined at age 7 years, the cord PCB concentration was associated with deficits on the Boston Naming Test (without cues, two-tailed P=.09 not adjusted for mercury; with cues, P=.03), the Continuous Performance Test reaction time (P=.03), and, possibly, on long-term recall on the California Verbal Learning Test (P=.15). The association between cord PCB and cord-blood mercury (r=.42) suggested possible confounding. While no PCB effects were apparent in children with low mercury exposure, PCB-associated deficits within the highest tertile of mercury exposure indicated a possible interaction between the two neurotoxicants. PCB-associated increased thresholds were seen at two of eight frequencies on audiometry, but only on the left side, and no deficits occurred on evoked potentials or contrast sensitivity. The limited PCB-related neurotoxicity in this cohort appears to be affected by concomitant methylmercury exposure.
Assuntos
Neurotoxinas/intoxicação , Bifenilos Policlorados/intoxicação , Efeitos Tardios da Exposição Pré-Natal , Desempenho Psicomotor/efeitos dos fármacos , Alimentos Marinhos/intoxicação , Criança , Estudos de Coortes , Dinamarca/etnologia , Relação Dose-Resposta a Droga , Feminino , Sangue Fetal/química , Humanos , Recém-Nascido , Inteligência , Aprendizagem/efeitos dos fármacos , Memória/efeitos dos fármacos , Testes Neuropsicológicos , Gravidez , Análise de Regressão , Escalas de WechslerAssuntos
Linfadenite/microbiologia , Tuberculose dos Linfonodos/diagnóstico , Adolescente , Adulto , Idoso , Criança , Pré-Escolar , Diagnóstico Diferencial , Feminino , Humanos , Masculino , PescoçoAssuntos
Traqueia/citologia , Idoso , Análise de Variância , Contagem de Células , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Mucosa/citologia , MucoRESUMO
The kinetics of formation of palladium dimethylglyoximate in the post-nucleation and pre-nucleation stages, and the effect of palladium on the reaction of biacetyl and hydroxylamine, have been studied.
RESUMO
The kinetics and mechanism of formation of dimethylglyoxime from biacetyl and hydroxylamine in acid solution have been studied. Unprotonated hydroxylamine was found to react with the hydrogen-bonded carbonyl group to give the conjugate acid of the oxime. Detectable quantities of carbinolamine intermediates were not found in the acid concentration range studied.
RESUMO
A spectrophotometric method was used to determine the acid dissociation constants of the conjugate acids of dimethylglyoxime and biacetyl monoxime. The dissociation constant, the acidity function and the absorbance of a mixture of protonated and unprotonated oxime were utilized to obtain the ultraviolet spectra of the protonated oxime.
RESUMO
A comparison of the reaction mechanisms by which nickel or palladium dimethylglyoximate is precipitated from homogeneous solution by the reactions of biacetyl and hydroxylamine discloses many differences. Knowledge of the kinetics and mechanism of the reactions can be used to avoid formation of excess dimethylglyoxime, a limitation of the conventional methods of precipitation.
