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Tracking blood lead and zinc protoporphyrin levels in Andean adults working in a lead contaminated environment

Fri, 04/03/2015 - 2:50pm

The purpose of this study was to investigate current blood lead (PbB) and zinc protoporphyrin (ZPP) levels in adults presently living in environmentally Pb-contaminated Andean communities, and to compare the findings with the PbB and ZPP levels of Pb-exposed adult cohorts from the same study area tested between 1996 and 2007. Blood samples from 39 adults were measured for PbB and ZPP concentrations. The current mean PbB level (22.7 mug/dl) was significantly lower than the mean (37.9 mug/dl) of the initial 1996 cohort. PbB levels for the 1997, 1998, 2003, and 2006 cohorts were also significantly lower than the levels for the 1996 group. Elevated ZPP/heme ratios of 103.3, 128.4, and 134.2 mumol/mol were not significantly different for the 2006, 2007, and 2012 groups, indicating chronic Pb exposure. While ZPP levels of Andean Ecuadorian Pb-glazing workers have remained elevated, PbB levels declined. Lead exposure of the workers needs to be continually monitored.

Declining blood lead and zinc protoporphyrin levels in Ecuadorian Andean children

Fri, 04/03/2015 - 2:50pm

OBJECTIVES: To investigate current lead (Pb) exposure in children living in Andean Ecuadorian communities. Blood Pb (PbB) and zinc protoporphyrin (ZPP) levels were used respectively as biomarkers of acute and chronic Pb poisoning. The current PbB-ZPP levels were compared with previous pediatric PbB-ZPP levels recorded over years in the study area.

DESIGN AND METHODS: Samples of whole blood were collected from 22 Andean children of Quechua and Mestizo backgrounds and measured for PbB concentrations by graphite furnace atomic absorption spectroscopy. ZPP/heme ratio and ZPP whole blood (ZPP WB) levels were measured with a hematofluorometer.

RESULTS: The mean PbB level for children in the current study group was 14.5 mug/dL, which was significantly lower than the mean PbB level of 41.1 mug/dL found in the same study area in the 1996-2000 test period, and lower than the 22.2 mug/dL mean level found in the 2003-2007 period. The current mean ZPP/heme ratio was 102.1 mumol/mol, and the mean ZPP WB level was 46.3 mug/dL, both lower than values previously found in children in the study area.

CONCLUSION: While the current pediatric PbB-ZPP levels in the study area remain elevated in some children, the overall levels indicate a decline relative to levels observed in the same Pb-contaminated area in the period between 1996 and 2007. The elevated ZPP levels suggest a history of chronic Pb exposure, and potential iron deficiency in some children. The overall reduction in PbB-ZPP levels suggests a positive outcome of a Pb-exposure education and prevention program, and the therapeutic intervention of succimer chelation therapy. Elsevier Inc. All rights reserved.

Persistence during extinction: examining the effects of continuous and intermittent reinforcement on problem behavior

Fri, 04/03/2015 - 2:50pm

This study examined behavioral persistence during extinction following continuous or intermittent reinforcement in the context of an analogue functional analysis of problem behavior. Participants were 4 children who had been diagnosed with an autism spectrum disorder and who engaged in problem behavior maintained by social reinforcement. Experimental sessions included 4 successive 5-min components: no social interaction, continuous or intermittent reinforcement for problem behavior (alternating across sessions), extinction, and no social interaction. All participants' problem behavior was more persistent during extinction following continuous reinforcement, suggesting that behavior during extinction was affected by the preceding schedule of reinforcement.

Membership of Defined Responses in Stimulus Classes

Fri, 04/03/2015 - 2:50pm

Sidman (2000) has suggested that in addition to conditional and discriminative stimuli, class-consistent defined responses can also become part of an equivalence class. In the current study, this assertion was tested using a mixed-schedule procedure that allowed defined response patterns to be "presented" as samples in the absence of different occasioning stimuli. Four typically developing adults were first trained to make distinct response topographies to two visual color stimuli, and then were taught to match those color stimuli to two different form-sample stimuli in a matching task. Three separate tests were given in order to determine whether training had established two classes each comprised of a response, a color, and a form: a form-response test in which the forms were presented to test if the participants would make differential responses to them; and two response-matching tests to test if the participants would match visual stimulus comparisons to response-pattern samples. Three of the four participants showed class-consistent responding in the tests, although some participants needed additional training prior to passing the tests. In general, the data indicated that the different response patterns had entered into a class with the visual stimuli. These results add to a growing literature on the role of class-consistent responding in stimulus class formation, and provide support for the notion that differential responses themselves can become a part of an equivalence class.

Visual field bias in hearing and deaf adults during judgments of facial expression and identity

Fri, 04/03/2015 - 2:50pm

The dominance of the right hemisphere during face perception is associated with more accurate judgments of faces presented in the left rather than the right visual field (RVF). Previous research suggests that the left visual field (LVF) bias typically observed during face perception tasks is reduced in deaf adults who use sign language, for whom facial expressions convey important linguistic information. The current study examined whether visual field biases were altered in deaf adults whenever they viewed expressive faces, or only when attention was explicitly directed to expression. Twelve hearing adults and 12 deaf signers were trained to recognize a set of novel faces posing various emotional expressions. They then judged the familiarity or emotion of faces presented in the left or RVF, or both visual fields simultaneously. The same familiar and unfamiliar faces posing neutral and happy expressions were presented in the two tasks. Both groups were most accurate when faces were presented in both visual fields. Across tasks, the hearing group demonstrated a bias toward the LVF. In contrast, the deaf group showed a bias toward the LVF during identity judgments that shifted marginally toward the RVF during emotion judgments. Two secondary conditions tested whether these effects generalized to angry faces and famous faces and similar effects were observed. These results suggest that attention to facial expression, not merely the presence of emotional expression, reduces a typical LVF bias for face processing in deaf signers.

Normative findings for periocular anthropometric measurements among Chinese young adults in Hong Kong

Fri, 04/03/2015 - 2:50pm

Measurement of periocular structures is of value in several clinical specialties including ophthalmology, optometry, medical and clinical genetics, oculoplastic surgery, and traumatology. Therefore we aimed to determine the periocular anthropometric norms for Chinese young adults using a noninvasive 3D stereophotography system. Craniofacial images using the 3dMDface system were acquired for 103 Chinese subjects (51 males and 52 females) between the ages of 18 and 35 years. Anthropometric landmarks were identified on these digital images according to standard definitions, and linear distances between these landmarks were calculated. It was found that ocular measurements were significantly larger in Chinese males than females for intercanthal width, biocular width, and eye fissure lengths. No gender differences were found in the eye fissure height and the canthal index which ranged between 43 and 44. Both right and left eye fissure height-length ratios were significantly larger in females. This is the first study to employ 3D stereophotogrammetry to create a database of anthropometric normative data for periocular measurements. These data would be useful for clinical interpretation of periocular pathology and serve as reference values when planning aesthetic and posttraumatic surgical interventions.

A 3D anthropometric analysis of the orolabial region in Chinese young adults

Fri, 04/03/2015 - 2:50pm

The orolabial region undergoes considerable changes after orthognathic surgery or orthodontic treatment. Ethnicity, age, and sex-specific norms are needed during the planning of interventions in this region. In 2008 the Br J Oral Maxillofac Surg published anthropometric measurements of the lips of Chinese children, but to our knowledge such reference data for young Chinese adults are not currently available. We therefore used digital anthropometry on 3-dimensional craniofacial images acquired from 103 healthy young Chinese adults with Class I skeletal pattern. Anthropometric landmarks were identified, which provided linear and angular measurements. All orolabial measurements were significantly larger in men than women, with the exception of the labiomental angle. In contrast, there were no sex differences in the anthropometric proportions. We therefore provide what we think are the first cross-sectional norms available for young Chinese adults. These norms can be used to evaluate the morphology of the lips objectively for preoperative diagnosis, planning of treatment, and assessment of postoperative outcomes. Published by Elsevier Ltd. All rights reserved.

Emotional facial and vocal expressions during story retelling by children and adolescents with high-functioning autism

Fri, 04/03/2015 - 2:50pm

PURPOSE: People with high-functioning autism (HFA) have qualitative differences in facial expression and prosody production, which are rarely systematically quantified. The authors' goals were to qualitatively and quantitatively analyze prosody and facial expression productions in children and adolescents with HFA.

METHOD: Participants were 22 male children and adolescents with HFA and 18 typically developing (TD) controls (17 males, 1 female). The authors used a story retelling task to elicit emotionally laden narratives, which were analyzed through the use of acoustic measures and perceptual codes. Naive listeners coded all productions for emotion type, degree of expressiveness, and awkwardness.

RESULTS: The group with HFA was not significantly different in accuracy or expressiveness of facial productions, but was significantly more awkward than the TD group. Participants with HFA were significantly more expressive in their vocal productions, with a trend for greater awkwardness. Severity of social communication impairment, as captured by the Autism Diagnostic Observation Schedule (ADOS; Lord, Rutter, DiLavore, and Risi, 1999), was correlated with greater vocal and facial awkwardness.

CONCLUSIONS: Facial and vocal expressions of participants with HFA were as recognizable as those of their TD peers but were qualitatively different, particularly when listeners coded samples with intact dynamic properties. These preliminary data show qualitative differences in nonverbal communication that may have significant negative impact on the social communication success of children and adolescents with HFA.

Go/No-Go Procedure with Compound Stimuli: Effects of Training Structure On the Emergence of Equivalence Classes

Fri, 04/03/2015 - 2:50pm

When the matching-to-sample (MTS) procedure is used, different training structures imply differences in the successive discriminations required in training and test conditions. When the go/no-go procedure with compound stimuli is used, however, differences in training structures do not imply such differences. This study assessed whether the go/no-go procedure with compound stimuli with different training structures would produce significant variations in emergent performances. Fourteen undergraduate students were divided into two training groups: OTM and MTO (one-to-many and many-to-one). During training, responses emitted in the presence of compounds defined as related were reinforced. Responses emitted in the presence of compounds defined as not-related were not. During tests, new compounds structurally emulated MTS equivalence tests. All participants finished training with comparable number of sessions and 13 of 14 showed emergent performances. These results suggest that differences in equivalence-test outcomes with OTM and MTO training structures in MTS procedures may be due to their different successive discrimination requirements.

Attention-deficit/hyperactivity disorder and obesity in US males and females, age 8-15 years: National Health and Nutrition Examination Survey 2001-2004

Fri, 04/03/2015 - 2:50pm

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT: Youth with ADHD may be at increased risk for obesity. Medications used to treat ADHD can affect weight. Few studies have investigated possible gender differences in associations between ADHD and obesity.

WHAT THIS STUDY ADDS: Nationally representative of US youth aged 8-15 years. Height and weight were measured, and ADHD assessed by structured diagnostic interview and parent report. Associations between ADHD and obesity are reported for males and females to enable gender comparisons.

OBJECTIVE: To investigate how associations between attention-deficit/hyperactivity disorder (ADHD) and obesity differ by gender and medication use in a nationally representative sample of US youth in which height and weight were measured.

METHODS: Youth age 8-15 (n = 3050) studied in the National Health and Nutrition Examination Survey 2001-2004. Obesity was defined as >/=95th percentile of US body mass index-for-age reference. ADHD was determined by asking parents if child had been diagnosed and using the Diagnostic Interview Schedule for Children IV. Gender-stratified multivariable logistic regression was used to estimate odds of obesity for youth with ADHD (medicated and unmedicated) relative to youth without ADHD.

RESULTS: Males with ADHD who were medicated had lower odds of obesity compared to males without ADHD (adjusted odds ratio [OR] = 0.42, 95% confidence interval [CI] = 0.23-0.78). Unmedicated males with ADHD were as likely as males without ADHD to be obese (adjusted OR = 1.02, 95% CI = 0.43-2.42). The odds of obesity for females taking medication for ADHD did not differ statistically from those of females without ADHD (adjusted OR = 1.21, 95% CI = 0.52-2.81). Females with ADHD not taking medication had odds of obesity 1.54 times those of females without ADHD; however, the 95% CI (0.79-2.98) was wide and not statistically significant at alpha = 0.05.

CONCLUSIONS: Associations between ADHD and obesity are influenced by treatment of ADHD with medication and may differ by gender. Youth with ADHD who are not treated with medication are as or more likely than youth without ADHD to be obese. the Study of Obesity.

Is body mass index a useful measure of excess body fatness in adolescents and young adults with Down syndrome?

Fri, 04/03/2015 - 2:50pm

BACKGROUND: To determine the validity of body mass index (BMI) to identify excess fatness in youth with Down syndrome (DS).

METHODS: Using the Centers for Disease Control and Prevention (CDC) growth reference, we defined overweight ( > = 85th percentile) and obesity ( > = 95th percentile) based on participants' age- and sex-specific BMI z-scores, calculated from measured height and weight. Percentage body fat was measured by dual-energy X-ray absorptiometry. We determined sensitivity, specificity, positive predictive value, negative predictive value and efficiency of BMI percentiles to identify excess adiposity relative to elevated percentage body fat cut-offs developed from the Pediatric Rosetta Body Composition project in 32 youth (20 boys/12 girls), ages 13-21 years with Down syndrome.

RESULTS: For adolescents with Down syndrome using the cut-off points of 95th percentile for BMI (obesity), sensitivity and specificity were 71% and 96% respectively. Positive predictive value was 83% and negative predictive value was 92%. Overall efficiency was 91%. Sensitivity and specificity for BMI cut-offs above the 85th percentile (overweight) were 100% and 60% respectively. The positive predictive value was 41% and negative predictive value was 100%. Overall efficiency was 69%.

CONCLUSION: On the whole, the obesity ( > = 95th percentile) cut-off performs better than the overweight cut-off (85th-94th percentile) in identifying elevated fatness in youth with DS. Wiley and Sons Ltd, MENCAP and IASSID.

Modeling the effects of sensory reinforcers on behavioral persistence with alternative reinforcement

Fri, 04/03/2015 - 2:50pm

Problem behavior often has sensory consequences that cannot be separated from the target response, even if external, social reinforcers are removed during treatment. Because sensory reinforcers that accompany socially mediated problem behavior may contribute to persistence and relapse, research must develop analog sensory reinforcers that can be experimentally manipulated. In this research, we devised analogs to sensory reinforcers in order to control for their presence and determine how sensory reinforcers may impact treatment efficacy. Experiments 1 and 2 compared the efficacy of differential reinforcement of alternative behavior (DRA) versus noncontingent reinforcement (NCR) with and without analog sensory reinforcers in a multiple schedule. Experiment 1 measured the persistence of key pecking in pigeons, whereas Experiment 2 measured the persistence of touchscreen responses in children with intellectual and developmental disabilities. Across both experiments, the presence of analog sensory reinforcers increased the levels, persistence, and variability of responding relative to when analog sensory reinforcers were absent. Also in both experiments, target responding was less persistent under conditions of DRA compared to NCR regardless of the presence or absence of analog sensory reinforcers.

Laser light scan analysis of the "anticonvulsant face"

Fri, 04/03/2015 - 2:50pm

BACKGROUND: The "anticonvulsant face," with a short nose, broad nasal bridge, epicanthal folds, and wide mouth, was described in the 1970s in children who had been exposed during pregnancy to the anticonvulsant drugs phenytoin and phenobarbital. The laser light scan makes it possible to establish three-dimensional positions of physical features and to determine more objectively the changes in the size and shape of the affected soft tissues of the faces of children exposed to these anticonvulsant drugs during pregnancy.

METHODS: Thirteen individuals, exposed throughout pregnancy to phenytoin as either monotherapy or polytherapy, were identified in a previous analysis as having significant changes in their craniofacial features based on measurements of cephalometric radiographs. Those changes were associated with midface hypoplasia and a short nose, features of the "anticonvulsant face." The soft tissues of their faces have been evaluated with laser light scans.

RESULTS: The notable changes in soft tissues identified by laser light scans were a wide philtrum (cph-cph), narrow mouth (ch-ch), short nasal bridge (n-prn), shortened nose height (n-sn), and flattened orbits (orbital protrusion index).

CONCLUSION: This analysis of the facial features of phenytoin-exposed individuals, selected because of changes in their craniofacial bony structures, showed that there were several significant changes, two of which, widening of the philtrum and a small mouth, have not been described previously as part of this phenotype.

Comparison of sedentary behaviors between children with autism spectrum disorders and typically developing children

Fri, 04/03/2015 - 2:50pm

Time spent in sedentary behavior is largely due to time spent engaged with electronic screen media. Little is known about the extent to which sedentary behaviors for children with autism spectrum disorder differ from typically developing children. We used parental report to assess and compare time spent in sedentary behaviors for 53 children with autism spectrum disorder and 58 typically developing children aged 3-11 years. We also determined how sedentary behavior was related to child weight status (body mass index z-score). Overall, children with autism spectrum disorder spent an hour more in sedentary behaviors on weekdays compared to typically developing children (5.2 vs 4.2 h, p = 0.03), and most of this difference was due to screen time. The age- and sex-adjusted estimate of weekday total daily screen time was 1.6 h (typically developing) compared to 2.5 h (autism spectrum disorder, p = 0.004 for difference). A significant relationship between BMI z-score and total sedentary behavior time on weekend days was observed among young children with ASD, but not among TD children. The modest association between weekend sedentary behaviour time and BMI z-score among children with ASD suggests that sedentary behaiour is linked to relative weight status in these children. Further research is needed to confirm these findings and identify causal pathways.

Obesity Prevention for Children with Developmental Disabilities

Fri, 04/03/2015 - 2:50pm

The prevention of obesity in children with DD is a pressing public health issue, with implications for health status, independent living, and quality of life. Substantial evidence suggests that children with developmental disabilities (DD), including those with intellectual disabilities (ID) and autism spectrum disorder (ASD), have a prevalence of obesity at least as high if not higher than their typically developing peers. The paper reviews what is known about the classic and unique risk factors for childhood obesity in these groups of children, including dietary, physical activity, sedentary behavior, and family factors, as well as medication use. We use evidence from the literature to make the case that primary prevention at the individual/family, school and community levels will require tailoring of strategies and adapting existing intervention approaches.

Rapid Teaching of Arbitrary Matching in Individuals with Intellectual Disabilities

Fri, 04/03/2015 - 2:50pm

This research extended to arbitrary matching-to-sample procedures a method that was successful in rapidly establishing identity matching in children with and without intellectual disabilities (Mackay et al., 2002). The method involves increasing the number of identical comparison stimuli in a choice array in order to create a homogenous background that makes the target more salient, thus likely to prompt selection. The number of comparison stimuli then is faded systematically contingent on accurate responding. This method unites cognitive research on visual search and behavior analytic research on conditional stimulus control. Two experiments examined use of the method to teach arbitrary relations between visual stimuli (numerals and colors and their printed names) and between visual and auditory stimuli (e.g., numerals and colors and their dictated names). Results demonstrated the generality of the method to symbolic matching. This finding is important for conceptual reasons and for its relevance to special education.

Thematic Matching as Remedial Teaching for Symbolic Matching for Individuals with Autism Spectrum Disorder

Fri, 04/03/2015 - 2:50pm

Matching-to-sample (MTS) is often used to teach symbolic relationships between spoken or printed words and their referents to children with intellectual and developmental disabilities. However, many children have difficulty learning symbolic matching, even though they may demonstrate generalized identity matching. The current study investigated whether training on symbolic MTS tasks in which the stimuli are physically dissimilar but members of familiar categories (i.e., thematic matching) can remediate an individual's difficulty learning symbolic MTS tasks involving non-representative stimuli. Three adolescent males diagnosed with autism spectrum disorder were first trained on symbolic MTS tasks with unfamiliar, non-representative form stimuli. Thematic matching was introduced after the participants failed to learn 0, 2 or 4 symbolic MTS tasks and before additional symbolic MTS tasks were introduced. After exposure to thematic matching, accuracy on symbolic MTS tasks with novel stimuli increased to above chance for all participants. For two participants, high accuracy ( > 90%) was achieved on a majority of these sessions. Thus, thematic matching may be an effective intervention for students with limited verbal repertoires and who have difficulty learning symbolic MTS tasks. Possible explanations for the facilitative effect of thematic matching are considered and warrant further investigation.

Stereophotogrammetry-based facial depth measurements: a novel method for quantifying facial projection

Fri, 04/03/2015 - 2:50pm

BACKGROUND: Orthognathic surgery leads to alteration of the spatial relationship of the mandible and maxilla resulting changes in the degree of facial projection. Traditional 2-dimensional cephalometry and photographic techniques do not provide data on facial depth. Though stereophotogrammetry can be used as a noninvasive method for evaluating facial depth, the unavailability of ethnicity-specific norms hinder its routine use in clinical practice. The objectives of this study were to (a) generate an analytic scheme suitable for evaluating facial depth using stereophotogrammetry and (b) create normative data for the facial depth measurements for young Hong Kong Chinese adults.

METHODS: Stereophotographic images from 41 male and 45 female ethnic Chinese young adults without facial deformities were analyzed. Facial depth measurements were performed based on standard anthropometric landmarks, with the aid of 3dMDVultus software.

RESULTS: All facial depth measurements were found in absolute terms to be significantly higher in males. In contrast, the upper face, maxillary, and sublabial depth indices were significantly higher in females, whereas no significant gender differences emerged for lower facial and maxillomandibular indices.

CONCLUSIONS: A novel method of using stereophotographic images for quantifying facial depth was evaluated. Normative facial depth measurements for young Hong Kong Chinese adults were established. This gender-specific database can be used as a reference in the diagnosis, treatment planning, or evaluation of outcomes after surgical correction of facial deformities.

Nasal Morphology of the Chinese: Three-Dimensional Reference Values for Rhinoplasty

Fri, 04/03/2015 - 2:50pm

OBJECTIVE: To determine normative nasal measurements for Chinese young adults, conditioned on demographics.

STUDY DESIGN: A cross-sectional descriptive study.

SETTING: A university hospital.

SUBJECTS AND METHODS: Three-dimensional (3D) photographs were captured from 103 Chinese subjects between 18 and 35 years of age using a commercial stereophotographic system. Anthropometric landmarks were identified on these 3D surface images, and measurements suitable for nasal analysis were performed and contrasted against established Caucasian norms. Gender differences in anthropometric dimensions were also analyzed.

RESULTS: Normative data for these measurements are made available. Linear nasal measurements, except those for mid-columella length, were significantly larger in men than in women; further, the nasal tip angle and nasofrontal angle were significantly larger in Chinese women. Contrasts of these new data against published Caucasian norms revealed dimensions that differ for these 2 groups. The Chinese normative mean values for morphological nose width, nasal tip angle, nasofrontal angle, and alar slope angle exceeded those reported for North American Caucasians.

CONCLUSIONS: Gender-specific normative data for the Chinese nose were established in this study to provide a useful tool for surgeons in dealing with rhinoplasty. Moreover, the Chinese nasal anthropometric measurements in this study are broader and flatter than those reported for North American Caucasians.

The potential influence of stimulus overselectivity in AAC: information from eye tracking and behavioral studies of attention with individuals with intellectual disabilities

Fri, 04/03/2015 - 2:50pm

This paper examines the phenomenon of stimulus overselectivity, or overselective attention, as it may impact AAC training and use in individuals with intellectual disabilities. Stimulus overselectivity is defined as an atypical limitation in the number of stimuli or stimulus features within an image that are attended to and subsequently learned. Within AAC, the term stimulus could refer to symbols or line drawings on speech-generating devices, drawings or pictures on low-technology systems, and/or the elements within visual scene displays. In this context, overselective attention may result in unusual or uneven error patterns such as confusion between two symbols that share a single feature, or difficulties with transitioning between different types of hardware. We review some of the ways that overselective attention has been studied behaviorally. We then examine how eye tracking technology allows a glimpse into some of the behavioral characteristics of overselective attention. We describe an intervention approach, differential observing responses, that may reduce or eliminate overselectivity, and we consider this type of intervention as it relates to issues of relevance for AAC.