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ABSTRACT: Although lead (Pb) exposure has been identified as an important risk factor in child behavioral development, less is known regarding the relation between child behavior and exposure to polychlorinated biphenyls (PCBs) and mercury (Hg). Inuit children are particularly exposed to these chemicals and the aim of this study was to investigate the association between prenatal and postnatal exposure to Pb, PCBs, Hg and several aspects of behavioral function in Inuit preschoolers. The sample consisted of one hundred and ten 5-year-old Inuit children from Arctic Quebec. An umbilical cord blood sample was used to document prenatal exposure to Pb, PCBs and Hg. Child blood samples were collected at age 5 and the same contaminants were measured. A modified version of the Infant Behavior Rating Scale from the Bayley Scales of Infant Development-II was used to assess child behavior through examiners' ratings. Furthermore, attention, activity and emotional outcomes were assessed through behavioral coding of video recordings taken during fine motor testing. Pb exposure during childhood was associated with examiners ratings of greater impulsivity, irritability and with coding of observed inattention. Prenatal exposure to PCB 153 correlated with the examiners ratings of increased state of unhappiness and anxiety during the testing session, which was corroborated from video coding since cord PCB 153 was related to fewer manifestations of positive affects. No association was found with Hg exposure. These data corroborated those from previous Pb cohort studies and revealed an association between prenatal PCBs exposure and emotional outcomes in preschoolers.
NeuroToxicology 10/2009; 31(1):17-25. · 3.10 Impact Factor
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Plant Cell. 01/2008; 20(11):3136-3147.
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ABSTRACT: Interindividual and intraindividual variability in neuromotor behaviors is expected and normal. Early changes in neuromotor behaviors associated with neurodegenerative disorders or neurotoxic effects are often subtle and fluctuating in their characteristics. Therefore, their detection at an early stage is particularly difficult without precise recording instruments. The CATSYS system developed by Danish Product Development (DPD) is a portable device recording four measures of neuromotor control including tremor, reaction time, hand coordination and postural sway. The aim of this study is to develop a set of normative data. One hundred and fifty healthy men and women were divided into five age groups: (1) 20 to 29 years (n=30); (2) 30 to 39 years (n=30); (3) 40 to 49 years (n=30); (4) 50 to 59 years (n=30); (5) 60 to 70 years (n=30). All participants were free of neurological deficits at the time of testing and they were tested individually for approximately 30 min. Hand coordination was measured with prono-supination and finger-tapping movements executed at constant and accelerated rhythms. Reaction time was assessed in both hands using a hand held switch activated by the thumb. Postural tremor was quantified in both hands during 24.6 sec. by asking the subject to hold a stylus horizontally at 10 cm in front of his/her navel. The stylus contained a biaxial accelerometer. Postural sway was tested by asking the subject to stand on a force platform for 75 sec. under four conditions: (1) eyes open; (2) eyes closed; (3) eyes open standing on a foam pad; and (4) eyes closed standing on a foam pad. ANOVAs and multiple comparison tests were performed and the results were examined taking into account age, gender and experimental condition effects.
NeuroToxicology 11/2000; 21(5):725-35. · 3.10 Impact Factor
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ABSTRACT: Elicitor-induced activation of the potato pathogenesis-related gene PR-10a requires a 30-bp promoter sequence termed the ERE (elicitor response element) that is bound by the nuclear factor PBF-2 (PR-10a binding factor 2). In this study, PBF-2 has been purified to near homogeneity from elicited tubers through a combination of anion-exchange and DNA affinity chromatography. Evidence demonstrates that inactive PBF-2 is stored in the nuclei of fresh tubers and becomes available for binding to the ERE upon elicitation. A protein with an apparent molecular mass of 24 kD (p24) is a DNA binding component of PBF-2. A cDNA encoding p24 has been cloned and encodes a novel protein with a potential transcriptional activation domain that could also act as a single-stranded DNA binding domain. Both PBF-2 and the cDNA-encoded protein bind with high affinity to the single-stranded form of the ERE in a sequence-specific manner. The inverted repeat sequence of the ERE, TGACAnnnnTGTCA, is critical for binding of this factor in vitro and for PR-10a expression in vivo, supporting the role of PBF-2 as a transcriptional regulator.
The Plant Cell 09/2000; 12(8):1477-89. · 8.99 Impact Factor
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ABSTRACT: The Arabidopsis NPR1 gene is essential in activating systemic, inducible plant defense responses. To gain a better understanding of NPR1 function, we conducted a yeast two-hybrid screening procedure and identified a differential interaction between NPR1 and all known members of the Arabidopsis TGA family of basic leucine zipper transcription factors. In the electrophoretic mobility shift assay, NPR1 substantially increased the binding of TGA2 to its cognate promoter element (as-1) as well as to a positive salicylic acid-inducible element (LS7) and a negative element (LS5) in the promoter of the pathogenesis-related PR-1 gene. Proteins encoded by npr1 mutants interacted poorly with TGA2 and did not substantially increase TGA2 binding to the as-1, LS5, or LS7 elements, thus establishing a link between the loss of disease resistance and the loss of TGA2 interaction and NPR1-enhanced DNA binding. Coupled with observations that the DNA binding activity of TGA factors is deregulated in npr1 plants, the results suggest that NPR1-mediated DNA binding of TGA2 is critical for activation of defense genes.
The Plant Cell 03/2000; 12(2):279-90. · 8.99 Impact Factor
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ABSTRACT: The elicitor-induced activation of the potato pathogenesis-related gene PR-10a is positively controlled by a protein kinase(s) that affects the binding of the nuclear factors PBF-1 (for PR-10a binding factor-1) and PBR-2 to an elicitor response element (ERE). In this study, we have identified a kinase that has properties similar to the conventional isoenzymes of the mammalian protein kinase C (PKC) family. the treatment of potato tuber discs with specific inhibitors of PKC abolished the elicitor-induced binding of the nuclear factor PBF-2 to the ERE. This correlated with a reduction in the accumulation of the PR-10a protein. In contrast, treatment of the tuber discs with 12-O-tetradecanoylphorbol 13-acetate (TPA), an activator of PKC, led to an increase in binding of PBF-2 to the ERE and the corresponding increase in the level of the PR-10a protein, mimicking the effect seen with the elicitor arachidonic acid. Biochemical characterization of proteins extracted from the particulate fraction of potato tubers demonstrated that a kinase belonging to the conventional isoforms of PKC is present. This was confirmed by immunoprecipitation with antibodies specific to the conventional isoforms of human PKC and in-gel kinase assays. The ability of the immunoprecipitates to phosphorylate the alpha-peptide (a PKC specific substrate) in the presence of the coactivators calcium, phosphatidylserine, and TPA strongly suggested that the immunoprecipitated kinase is similar to the kinase characterized biochemically. Finally, the similar effects of the various modulators of PKC activity on the elicitor-induced resistance against a compatible race of Phytophthora infestans implicate this kinase in the overall defense response in potato.
The Plant Cell 05/1997; 9(4):653-64. · 8.99 Impact Factor
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ABSTRACT: Spasmophilia is a relatively unknown condition characterized by perturbations of the neuromuscular system. We hypothesized that spasmophilia may negatively affect neuromotor functions in subtle ways. Three tests including tremor, rapid pointing movements, and alternating movements were quantified in a group of subjects with spasmophilia symptoms (SS) (n = 10) and a healthy control group (n = 10). Most of the characteristics used to evaluate motor functions in these three tests revealed no significant differences between the two groups except for two characteristics in alternating movements and two characteristics in rapid pointing movements. In terms of variances, a dissociation between voluntary movements and involuntary movements was observed for the two groups. Control subjects had significantly higher variances in involuntary movements such as tremor, while subjects with SS had significantly higher variances in voluntary movements such as alternating and rapid pointing movements. A significant increase in asymmetry in hand laterality was also noted for some characteristics in subjects with SS.
Brain and Cognition 43(1-3):143-7. · 3.17 Impact Factor
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ABSTRACT: The main focus of this study was to determine the role of behaviour in the relationship between postnatal lead exposure and motor function. The sample consisted of 110 preschoolers, of age 5, from Nunavik. Lead concentration was measured at birth and at testing time. Average lead levels were of 4.9 microg/dL (0.24 micromol/L) and 5.3 microg/dL (0.26 micromol/L) for cord and child blood, respectively. Children's balance and fine motor capacities were tested. A modified version of the IBR was used to assess behaviour. Postnatal blood lead concentrations correlated positively with both impulsivity and activity. Neither pre- nor postnatal blood lead concentration correlated with attention level. The children's scores on impulsivity (I) and activity (A) were summed to create the independent variable IA, which was tested as a potential mediator between lead exposure and two dependent variables: the coefficient of covariation in alternating hand movements and transversal sway in tandem position. Mediation was significant only for the latter variable. IA and attention were then tested as potential moderators in the relation between postnatal lead exposure and motor function. No significant interaction between independent variables could be observed. These results do not support the hypothesis that, at low levels of postnatal exposure, lead acts indirectly on motor function via behaviour. However, IA does act as a mediator in the relationship between postnatal blood lead concentration and transversal sway in tandem position.
Neurotoxicology and Teratology 28(1):18-27. · 2.98 Impact Factor
