A plateau detected in lead accumulation in subsurface deciduous enamel from individuals exposed to lead may be useful to identify children and regions exposed to higher levels of lead

In a previous study, we showed 4 times more lead in surface deciduous enamel (1.9-5.9 mu m) of a notoriously contaminated area (Bauru, Sao Paulo State, Brazil) in comparison to samples from a region with no lead contamination described (Ribeirao Preto, Sao Paulo State, Brazil). The samples from the more superficial enamel (1.9-3.18 mu m) showed higher amounts of lead and the highest variability, while in the subsurface enamel (3.18-5.9 mu m) a plateau in lead content was detected in children living in the contaminated environment (around 600 mu g/g). Here we expand our previous study, and use only samples obtained from subsurface enamel (Ribeirao Preto, n = 186; Bauru, n = 20). We tried to distinguish regions with more children with lead above the threshold of 600 mu g/g of lead in enamel. We tested whether differences in the percentage of children with ""high"" lead (>= 600 mu g/g) could be observed among the different Kindergartens studied in Ribeirao Preto. We also tested whether these results were different from the ones provided by conventional comparison of the data. Ribeirao Preto showed almost 4 times less lead than Bauru (p < 0.0001), and a statistically significant difference was found only in Ribeirao Preto between Kindergarten 2 and 5 (p<0.01). Twelve percent of the children from Ribeirao Preto had ""high"" lead, while 55% of the children from Bauru did so. However, when we looked at the percentages of children with ""high"" lead in each Kindergarten, and compared them, a whole new picture emerged, in which we could see children with ""high"" lead concentrated mainly in 3 Kindergartens from Ribeirao Preto, with Kindergarten 5 with 33% of the children with ""high"" lead, being statistically different from all Kindergartens, except 4 and 6. The threshold of 600 mu g/g of lead in subsurface enamel was tentatively settled here after the plateau seen in exposed children, and enabled us to identify locations with more children exposed to a higher amount of lead. (C) 2008 Elsevier Inc. All rights reserved.

Haplotypes of vitamin D receptor modulate the circulating levels of lead in exposed subjects

Genetic factors influence whole blood lead (Pb-B) concentrations in lead exposed subjects. This study aimed at examining the combined effects (haplotype analysis) of three polymorphisms (BsmI, ApaI and FokI) in vitamin D receptor (VDR) gene on Pb-B and on the concentrations of lead in plasma (Pb-P), which is more relevant to lead toxicity, in 150 environmentally exposed subjects. Genotypes were determined by RFLP, and Pb-P and Pb-B were determined by inductively coupled plasma mass spectrometry and by graphite furnace atomic absorption spectrometry, respectively. Subjects with the bb (BsmI polymorphism) or ff (FokI polymorphism) genotypes have lower B-Pb than subjects in the other genotype groups. Subjects with the aa (ApaI polymorphism) or ff genotypes have lower P-Pb than subjects in the other genotype groups. Lower Pb-P, Pb-B, and %Pb-P/Pb-B levels were found in subjects with the haplotype combining the a, b, and f alleles for the ApaI, BsmI, and FokI polymorphisms, respectively, compared with the other haplotype groups, thus suggesting that VDR haplotypes modulate the circulating levels of lead in exposed subjects.

Exposure to contaminated water: perceptions and practices in a neighborhood in the city of Manaus, Brazil

Objective. To investigate the modes of water supply and the perception concerning the problems caused by this water among residents of a neighborhood without public supply of water, settled in an area previously used as a garbage dump in the city of Manaus, Brazil. Methods. One hundred and sixty-two semi-structured household interviews were conducted. In addition, a focal group with teachers from a local public school and a meeting with residents were held. The instruments employed focused on the perception and modes of water use and on the process of exposure to chemical contaminants through water. Results. Untreated well water was used by most families. This water was considered to be ""good"" by 64.8% of the individuals interviewed. Most residents (88.3%) declared knowledge about the garbage dump. Of these, 77.6% stated that the garbage dump caused health and environmental problems. However, qualitative analysis of the responses revealed that the residents were not aware of contamination by chemical elements or of the consequences of such contamination. The activities carried out with teachers revealed that they were partially aware of the problem, but did not design interventions to address the issue. In a meeting with neighborhood residents, the presence of social activism concerning the problem was identified, but it did not extend beyond the neighborhood or reach governmental spheres. Conclusions. The study identified a situation of critical exposure that tends to be maintained as a result of misperceptions and lack of social mobilization. The dissemination of research results to teachers and residents was useful to empower subjects.

Polarized photoluminescence from surface-passivated lead sulfide nanocrystals

Effective surface passivation of lead sulfide (PbS) nanocrystals (NCs) in an aqueous colloidal solution has been achieved following treatment with CdS precursors. The resultant photoluminescent emission displays two distinct components, one originating from the absorption band edge and the other from above the absorption band edge. We show that both of these components are strongly polarized but display distinctly different behaviours. The polarization arising from the band edge shows little dependence on the excitation energy while the polarization of the above-band-edge component is strongly dependent on the excitation energy. In addition, time-resolved polarization spectroscopy reveals that the above-band-edge polarization is restricted to the first couple of nanoseconds, while the band edge polarization is nearly constant over hundreds of nanoseconds. We recognize an incompatibility between the two different polarization behaviours, which enables us to identify two distinct types of surface-passivated PbS NC.

Investigation of the role of cadmium sulfide in the surface passivation of lead sulfide quantum dots

Surface passivation of PbS nanocrystals (NC), resulting in strong photoluminescence, can be achieved by the introduction of CdS precursors. The role of CdS in the surface passivation of PbS NCs is uncertain, as the crystalline structure of CdS and PbS are different, which should impede effective epitaxial overgrowth. Absorption spectroscopy is used to show that the CdS precursors strongly interact with the PbS NC surface. Electron microscopy reveals that the introduction of CdS precursors results in an increased particle size, consistent with overcoating. However, we also find the process to be highly non-uniform. Nevertheless, evidence for epitaxial growth is found, suggesting that effective surface passivation may be possible.

Knowing your allies: Medical education and interprofessional exposure

Collaborative, team-based, interprofessional approaches to patient management are becoming increasingly recognized as beneficial to health outcomes. This project aimed to develop interprofessional skills among 134 third year medical students that were of clinical educational value to the students, and through activities that directly benefited the rural health professionals in their daily work. Placements were undertaken during a six week rural clinical attachment, mainly throughout South-West Queensland. Pre- and post-placement self-report questionnaires completed by both students and health professionals were used to evaluate the project. Results showed that over 80% of the health professional group reported the medical student placements were useful. Similarly, almost 80% of medical students reported positive changes in their attitude to other health professionals from the placement, and 91% indicated they had derived clinical educational benefit from their interprofessional activity. Despite difficulties due to poor communication between the various parties involved, the project proved successful in improving medical students' skills, knowledge and perceptions concerning interprofessional practice, through a placement and educational project which delivered practical benefits to rural health professionals and rural communities.

Reducing problem behavior during care-giving in families of preschool-aged children with developmental disabilities

This study evaluated two variants of a behavioral parent training program known as Stepping Stones Triple P (SSTP) using 74 preschool-aged children with developmental disabilities. Families were randomly allocated to an enhanced parent training intervention that combined parenting skills and care-giving coping skills (SSTP-E), standard parent training intervention alone (SSTP-S) or waitlist control (WL) condition. At post-intervention, both programs were associated with lower levels of observed negative child behavior, reductions in the number of care-giving settings where children displayed problem behavior, and improved parental competence and satisfaction in the parenting role as compared with the waitlist condition. Gains attained at post-intervention were maintained at 1-year follow-up. Both interventions produced significant reductions in child problem behavior, with 67% of children in the SSTP-E and 77% of children in the SSTPS showing clinically reliable change from pre-intervention to follow-up. Parents reported a high level of satisfaction with both interventions.

The effects of prepulse-blink reflex trial repetition and prepulse change on blink reflex modification at short and long lead intervals

Prepulse inhibition and facilitation of the blink reflex are said to reflect different responses elicited by the lead stimulus, transient detection and orienting response respectively. Two experiments investigated the effects of trial repetition and lead stimulus change on blink modification. It was hypothesized that these manipulations will affect orienting and thus blink facilitation to a greater extent than they will affect transient detection and thus blink inhibition. In Experiment 1 (N = 64), subjects were trained with a sequence of 12 lead stimulus and 12 blink stimulus alone presentations, and 24 lead stimulus-blink stimulus pairings. Lead interval was 120 ms for 12 of the trials and 2000 ms for the other 12. For half the subjects this sequence was followed by a change in pitch of the lead stimulus. In Experiment 2 (N = 64), subjects were trained with a sequence of 36 blink alone stimuli and 36 lead stimulus-blink stimulus pairings. The lead interval was 120 ms for half the subjects and 2000 ms for the other half. The pitch of the lead stimulus on prestimulus trials 31-33 was changed for half the subjects in each group. In both experiments, the amount of blink inhibition decreased during training whereas the amount of blink facilitation remained unchanged. Lead stimulus change had no effect on blink modification in either experiment although it resulted in enhanced skin conductance responses and greater heart rate deceleration in Experiment 2. The present results are not consistent with the notion that blink facilitation is linked to orienting whereas blink inhibition reflects a transient detection mechanism. (C) 1998 Elsevier Science B.V.

Photoinhibition in differently coloured juvenile leaves of Syzygium species

Photoinhibition, as measured by the dark-adapted chlorophyll a fluorescence ratio F-v/F-m, was assessed in Syzygium moorei, a species with dark green juvenile leaves, Syzygium corynanthum, which has light green juvenile leaves, and two species with pink-red juvenile leaves (Syzygium wilsonii and Syzygium luehmannii). All plants were glasshouse-grown (maximum PPFD 1500 mu mol m(-2) s(-1)) under optimum nutrition and water. When measured at midday, dark-adapted F-v/F-m ratios of juvenile leaves gradually increased in art species as percentage of full leaf expansion (% FLE) increased. Fluorescence measurement 3 h after sunset or pre-dawn also showed a developmental effect on F-v/F-m, with juvenile leaves of S, luehmannii and S. wilsonii showing much lower F-v/F-m at all stages of development. Dark-adapted F-v/F-m values in both juvenile and mature leaves generally never exceeded 0.8 at any stage in any of the species. Courses of F-v/F-m on sunny days showed greater diurnal photoinhibition in green juvenile (c, 50% FLE) leaves of S, moorei (24%) and S, corynanthum (36%) than in mature leaves of the previous flush in these species (<10%), Diurnal photoinhibition was statistically similar (18-24%) in pink-red juvenile and green mature leaves of S, luehmannii and S, wilsonii. Re-positioning juvenile leaves of S, wilsonii horizontally increased diurnal photoinhibition, Exposure of leaves to a standard mild photoinhibitory right treatment (30 min at 1000 mu mol m(-2) s(-1)) showed that juvenile leaves of air species had a lower percentage of high energy state quenching (qE) and a higher percentage of photoinhibitory quenching (ql) than mature leaves.

Coronary events and exposure to environmental tobacco smoke: a case-control study from Australia and New Zealand

Objectives-To estimate the relative risk of coronary heart disease (CHD) associated with exposure to environmental tobacco smoke (ETS). Design-Population-based case-control study. Subjects-Cases were 953 people identified in a population register of coronary events, and controls were 3189 participants in independent community-based risk factor prevalence surveys from the same study populations. Setting-Newcastle, Australia and Auckland, New Zealand. Main outcome measures-Acute myocardial infarction or coronary death. Results-After adjusting for the effects of age, education, history of heart disease, and body mass index, women had a statistically significant increased risk of a coronary event associated with exposure to ETS (relative risk (RR) = 1.99; 95% confidence interval (CI)= 1.40-2.81). There was little statistical evidence of increased risk found in men (RR = 1.02, 95% CI = 0.81-1.28). Conclusion-Our study found evidence for the adverse effects of exposure to ETS on risk of coronary heart disease among women, especially at home. For men the issue is unclear according to the data from our study. Additional studies with detailed information on possible confounders and adequate statistical power are needed. Most importantly, they should use methods for measuring exposure to ETS that are sufficiently accurate to permit the investigation of dose-response relationships.

Chronic ethanol exposure and withdrawal influence NMDA receptor subunit and splice variant mRNA expression in the rat cerebral cortex

Chronic ethanol exposure and subsequent withdrawal are known to change NMDA receptor activity. This study examined the effects of chronic ethanol administration and withdrawal on the expression of several NMDA receptor subunit and splice variant mRNAs in the rat cerebral cortex. Ethanol dependence was induced by ethanol vapour exposure. To delineate between seizure-induced changes in expression during withdrawal and those due to withdrawal per se, another group of naive rats was treated with pentylenetetrazol (PTZ) injection (30 mg/kg, i.p.). RNA samples from the cortices of chronically treated and withdrawing animals were compared to those from pairfed controls. Changes in NMDA receptor mRNA expression were determined using ribonuclease protection assays targetting the NR2A, -2B, -2C and NR1-pan subunits as well as the three alternatively spliced NR1 inserts (NR1-pan describes all the known NR1 splice variants generated from the 5' insert and the two 3' inserts). The ratio of NR1 mRNA incorporating the 5' insert vs, that lacking it was decreased during ethanol exposure and up to 48 h after withdrawal. NR2B mRNA expression was elevated during exposure, but returned to control levels 18 h after withdrawal. Levels of NR2A, NR2C, NR1-pan and both 3' NR1 insert mRNAs from the ethanol-treated groups did not alter compared with the pair-fed control group. No changes in the level of any NMDA receptor subunit mRNA was detected in the PTZ-treated animals. These data support the hypothesis that changes in NMDA receptor subunit composition may underlie a neuronal adaptation to the chronic ethanol-inhibition and may therefore be important in the precipitation of withdrawal hyperactivity. (C) 1999 Elsevier Science B.V. All rights reserved.