Spatially resolved hazard and exposure assessments: an example of lead in soil at Lavrion, Greece.

Spatially resolved hazard assessment (SRHA) and spatially resolved exposure assessment (SREA) are methodologies that have been devised for assessing child exposure to soil containing environmental pollutants. These are based on either a quantitative or a semiquantitative approach. The feasibility of the methodologies has been demonstrated in a study assessing child exposure to Pb accessible in soil at the town of Lavrion in Greece. Using a quantitative approach, both measured and kriged concentrations of Pb in soil are compared with an "established" statutory threshold value. The probabilistic approach gives a refined classification of the contaminated land, since it takes into consideration the uncertainty in both the actual measurement and estimated kriged values. Two exposure assessment models (i.e., IEUBK and HESP) are used as the basis of the quantitative SREA methodologies. The significant correlation between the blood-Pb predictions, using the IEUBK model, and measured concentrations provides a partial validation of the method, because it allows for the uncertainty in the measurements and the lack of some site-specific measurements. The semiquantitative applications of SRHA and SREA incorporate both qualitative information (e.g., land use and dustiness of waste) and quantitative information (e.g., distance from wastes and distance from industry). The significant correlation between the results of these assessments and the measured blood-Pb levels confirms the robust nature of this approach. Successful application of these methodologies could reduce the cost of the assessment and allow areas to be prioritized for further investigation, remediation, or risk management.

Progressive tricuspid valve disease in patients with congenitally corrected transposition of the great arteries.

BACKGROUND: The outcome of patients with corrected transposition of the great arteries (CTGA) is variably affected by associated intracardiac defects, tricuspid valve competence, and systemic right ventricular (RV) function. The relative importance of these factors in long-term outcome has not been evaluated. METHODS AND RESULTS: Since 1958, 40 patients with CTGA were studied to determine risk factors for poor outcome, including age, open heart surgery, tricuspid insufficiency (TI), cardiac rhythm, pulmonary overcirculation, and RV dysfunction. Follow-up ranged from 7 to 36 years (mean 20 years). Intracardiac repair was performed in 21 patients; 19 were unoperated or had closed heart procedures. For the purposes of this study the designation TI(S) refers to at least moderately severe TI as delineated by echocardiogram and/or angiography. TI(s) was the only independently significant factor for death (P=0.01), and in turn, only the presence of a morphologically abnormal TV predicted TI(s)(P=0.03). Twenty-year survival without TI(S)was 93%, but only 49% with TI(S). Poor long-term postoperative outcome was due to TI(S) in all but 1 patient; 20-year survival rates for operated patients with and without TI(s)were 34% and 90%, respectively (P=0.002). Similarly, 20-year survival rates for unoperated patients with and without TI(s)were 60% and 100%, respectively, whether or not attempts to repair the TI were made (P=0.08). CONCLUSIONS: TI(S)represents the major risk factor for CTGA patients; RV dysfunction appears to be almost always secondary to long-standing TI. Decisions related to surgical interventions with or without associated lesions must be strongly influenced by the status of the tricuspid valve.

Immediate reproducibility of electrically induced sustained monomorphic ventricular tachycardia before and during antiarrhythmic therapy.

The immediate reproducibility of sustained ventricular tachycardia induction was evaluated prospectively during 106 studies performed in 53 patients with clinical sustained monomorphic ventricular tachycardia. Programmed electrical stimulation was performed twice, using the same protocol during 53 drug-free studies and 53 subsequent studies on antiarrhythmic therapy. Sustained monomorphic ventricular tachycardia was reproduced in 104 (98%) of the 106 studies. There was no significant difference in the incidence of reproducible tachycardia in the drug-free state compared with that observed during treatment with different classes of antiarrhythmic drugs. An increase in the number of extrastimuli was required to reinitiate the tachycardia in 9 (11%) of 83 studies in which single or double extrastimuli were initially required to induce the tachycardia. In 39 (37%) of 104 studies with reproducible tachycardia induction, the two tachycardias significantly differed in electrocardiographic (ECG) configuration and cycle length. These observations suggest that the overall reproducibility of ventricular tachycardia induction is sufficiently high to provide a reliable marker for evaluating the efficacy of therapeutic interventions. However, specific tachycardia characteristics such as cycle length and ECG configuration are more variable even within the same study and may be less useful in assessing the effects of subsequent interventions.

A nonendocytotic mechanism for the selective uptake of high density lipoprotein-associated cholesterol esters.

We have previously described in rats the selective uptake of HDL-associated cholesterol esters (traced by [3H]cholesteryl oleyl ether) in excess of the uptake of HDL-associated apoA-I. In the present studies we show that the mechanism also exists in cultured cells of human and mouse origin as well. This selective uptake represents a net uptake of cholesterol esters and not an isotope exchange, as shown by mass flux studies in adrenal cells. Inhibitors of receptor recycling, chloroquine, monensin, and colchicine, inhibited uptake of apoA-I from HDL by Hep G-2 human hepatoma cells to about the same extent as a reference protein, asialofetuin, but inhibited uptake of the cholesteryl ether tracer much less. Levels of NaN3 which effectively inhibited sucrose pinocytosis inhibited uptake of apoA-I to about the same extent but did not inhibit uptake of the cholesteryl ether at all. Thus, not only receptor recycling, but endocytosis as well, appears not to be involved in selective uptake. This conclusion was supported by studies in which synthetic HDL particles were made to contain two neutral lipid core tracers; one of them, the [3H]cholesteryl ether previously used, was selectively taken up, whereas the other, [14C]sucrose octaoleate, was excluded from selective uptake. Thus, selective uptake cannot involve endocytosis of the entire lipid core, but may involve other specific transfer mechanisms.

Applicability of the Denver Prescreening Developmental Questionnaire in a low-income population.

A prospective study was conducted to assess the applicability of the Denver Prescreening Developmental Questionnaire (DPDQ) in a predominantly black, low-income population in Mobile, Alabama. The effect of an educational intervention designed to increase the accuracy of parental responses to the DPDQ was also assessed. In a longitudinal follow-up program, 127 infants aged 2 weeks to 1 year were recruited. Parents in a randomly selected experimental group observed an audio-visual presentation describing progressive developmental behaviors, received handout materials summarizing these behaviors, and were asked to record their child's subsequent attainment of these behaviors. Mean agreement scores, obtained by comparing parental responses to the DPDQ with the corresponding items of the Denver Developmental Screening Test (DDST), did not differ between the experimental and control groups. These scores showed agreement of 93.6% (3-month visit), 91.3% (6-month visit), 91.6% (9-month visit), and 95.1% (12-month visit), resulting in an overall mean agreement score of 92.9%. The overreferral rate was low (13%) and no underreferrals were obtained. These results attest to the applicability of the DPDQ in low-income population and demonstrate the lack of effectiveness of the educational intervention in increasing the accuracy of parental responses to the DPDQ.

Treating hair pulling in a 7-year-old male: modified habit reversal for use in pediatric settings.

In pediatric office settings children with nervous habits, such as hair pulling, are often treated with drugs or referred for psychological treatment. The habit reversal technique, a behavior therapeutic approach to treating nervous habits, has proven cost-efficient in terms of maximal benefit from a minimal therapeutic intervention. However, this technique has not been considered practical to use in pediatric office settings because of the therapist-client contact time required. The present case study focused on treating hair pulling in a 7-year-old boy using a modified version of the habit reversal technique. Following a single 20-minute session, hair pulling was eliminated and did not recur throughout an 18-month follow-up. Although additional data are needed prior to advocating general use of this approach, the preliminary results suggest the feasibility of the modified habit reversal technique for treating nervous habits in children in pediatric office settings.

Pediatric counseling with parents regarding childhood behavior problems: misbehavior away from home and early morning dawdlers.

The role of the pediatrician is being expanded to encompass parent counseling regarding childhood behavior problems. The most commonly used techniques have included praise for appropriate behavior combined with ignoring inappropriate behavior and / or providing time out for misbehavior. The present paper presents two techniques (i.e., a modified time out procedure and a response cost procedure) with which pediatricians can counsel parents regarding how to manage discipline problems outside the home and difficulties associated with children's morning routines in preparation for school.

Self-control training in the classroom: a review and critique.

Self-control training in classroom settings is becoming widespread. Establishing effective self- rather than externally controlled behavior modification programs in schools would enable children to control their own academic and social behavior, while enabling teachers to devote more time to teaching. The following components of self-control are reviewed in the present article: self-recording, self-evaluation, self-determination of contingencies, and self-instruction. Self-control strategies designed for the maintenance of appropriate classroom behavior, and issues associated with self-control training, such as the reliability of self-observation, response maintenance, generalization, and the role of external control, are examined. Finally, suggestions for maximizing the potential effectiveness of self-control training in the classroom (e.g., teaching self-observational procedures, teaching students to provide themselves with instructions and praise), as well as future areas for experimental investigation (e.g., social changes that may be associated with self-control procedures), are presented.

The development and functional control of reading-comprehension behavior.

Reading comprehension, indicated by motor behavior and multiple-choice picture selection called for in written instructions, was taught to an autistic child using verbal prompts, modelling, and physical guidance. The child was rewarded for correct behaviors to training items; nonrewarded probes were used to assess generalization. Probable maintaining events were assessed through their sequential removal in a reversal design. Results showed: (a) following acquisition, performance was maintained at a near-100% level when candy, praise, attention, and training were removed, (b) absence of other persons was correlated with a marked decrease in performance, whereas their presence was associated with performance at near 100%, and (c) performance generalized to probes and across experimenters. Rewards, which may have been reinforcing during acquisition, did not appear necessary to maintain later performance. Instead, presence of others (a setting event) was demonstrated to have control over maintained performance.