Charon's size and an upper limit on its atmosphere from a stellar occultation.

Pluto and its satellite, Charon (discovered in 1978; ref. 1), appear to form a double planet, rather than a hierarchical planet/satellite couple. Charon is about half Pluto's size and about one-eighth its mass. The precise radii of Pluto and Charon have remained uncertain, leading to large uncertainties on their densities. Although stellar occultations by Charon are in principle a powerful way of measuring its size, they are rare, as the satellite subtends less than 0.3 microradians (0.06 arcsec) on the sky. One occultation (in 1980) yielded a lower limit of 600 km for the satellite's radius, which was later refined to 601.5 km (ref. 4). Here we report observations from a multi-station stellar occultation by Charon, which we use to derive a radius, R(C) = 603.6 +/- 1.4 km (1sigma), and a density of rho = 1.71 +/- 0.08 g cm(-3). This occultation also provides upper limits of 110 and 15 (3sigma) nanobar for an atmosphere around Charon, assuming respectively a pure nitrogen or pure methane atmosphere.

Oxytocin and autistic disorder: alterations in peptide forms.

BACKGROUND: Oxytocin (OT) is synthesized as a prohormone that is sequentially processed to peptides. These peptides are the bioactive amidated form (OT) and the C-terminal extended peptides, OT-Gly, OT-Gly-Lys and OT-Gly-Lys-Arg, which are designated together as OT-X. As an extension of our previous study finding decreased plasma OT in autism, studies were conducted to determine whether there were changes in OT peptide forms in autistic children. METHODS: Twenty eight male subjects (97 +/- 20 months; range, 70-139 months), diagnosed with DSM-IV autistic disorder through observation and semi-structured interview, were compared with 31 age-matched nonpsychiatric control subjects (106 +/- 22 months; range, 74-140 months). Using OT antisera with different specificity for the peptide forms, we measured plasma OT and OT-X in each group. RESULTS: T tests showed that there was a decrease in plasma OT (t = 4.4, p <.0001), an increase in OT-X (t = 2.3, p <.03) and an increase in the ratio of OT-X/OT (t = 4.5, p <.0001) in the autistic sample, compared with control subjects. CONCLUSIONS: The results suggest that children with autistic disorder show alterations in the endocrine OT system. Deficits in OT peptide processing in children with autism may be important in the development of this syndrome.

Predictors and correlates of adaptive functioning in children with developmental disorders.

Autism is a developmental disorder marked by impairments in socialization, communication, and perseverative behavior and is associated with cognitive impairment and deficits in adaptive functioning. Research has consistently demonstrated that children with autism have deficits in adaptive functioning more severe than their cognitive deficits. This study investigates the correlates and predictors of adaptive functioning as measured by the Vineland Adaptive Behavior Scales in high- and low-functioning children with autism and their age and nonverbal IQ matched controls. Thirty-five 9-year-old children with high-functioning autism (HAD) were compared with 31 age-matched children with developmental language disorder (DLD), and 40 9-year-old children with low-functioning autism (LAD) were compared with 17 age-matched children with low IQ on adaptive functioning, IQ, autistic symptomology, and tests of language and verbal memory. Results indicate that both groups with autism were significantly impaired compared to their matched controls on Socialization and Daily Living, but not Communication and that these impairments were more pronounced in the HAD group than in the LAD group. Adaptive behavior was strongly correlated with autistic symptomology only in the HAD group. Regression analyses indicated that IQ was strongly predictive of adaptive behavior in both low-functioning groups, but tests of language and verbal memory predicted adaptive behavior in the higher functioning groups. Results suggest that IQ may act as a limiting factor for lower functioning children but higher functioning children are impaired by specific deficits, including autistic symptomology and impaired language and verbal memory.

Autistic disorder versus other pervasive developmental disorders in young children: same or different?

Eighteen preschool children diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders Third Edition Revised (DSM III-R) as having Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS) were compared to 176 children with DSM III-R Autistic Disorder (AD), and to 311 non-autistic children with developmental language disorders (DLD) (N = 201) or low IQ (N = 110). All children were partitioned into "high" and "low" cognitive subgroups at a nonverbal IQ of 80. Within cognitive subgroups, the 18 PDD-NOS children did not differ significantly from either the DLD or the AD children in verbal and adaptive skills and obtained scores intermediate between those of these groups. The PDD-NOS did not differ from the AD children in maladaptive behaviors. Both the PDD-NOS and AD children had many more of these behaviors than the non-autistic comparison groups. Children in the "high" and "low" cognitive subgroups of AD, but not of PDD-NOS, differed substantially on most measures, with the children with lower cognitive scores significantly more impaired on all measures. Similarity of PDD-NOS children to AD children in maladaptive behaviors and an intermediate position between autistic and non-autistic groups on virtually all measures explains the difficulty clinicians encounter in classifying children with PDD and raises questions about the specificity of these diagnostic subtypes of the autistic spectrum.

Executive functioning in high-functioning children with autism.

Executive functioning was investigated in 34 children (24 boys and 10 girls) with developmental language disorder (DLD) and 21 children (18 boys and 3 girls) with high-functioning autistic disorder (HAD) matched on Full Scale IQ, Nonverbal IQ, age (mean age 9 year, 1 month), and SES. The DLD group had a Verbal IQ that was 10 points higher than the HAD group. These children were given the Wisconsin Card Sorting Test (WCST), the Mazes subtest from the WISC-R, the Underlining test, and the Rapid Automatized Naming test. In addition, these children were given the Vineland Scales of Adaptive Functioning and the Wing Diagnostic Symptom Checklist in order to assess severity of autistic symptomatology. Results indicated that the only significant difference between the two groups on the cognitive tasks was perseverative errors on the WCST; there was no significant difference on total number of categories achieved or total number of errors on the WCST or on the other executive function measures. There was also significant overlap in the scores between the two groups and the difference in perseverative errors was no longer significant when Verbal IQ was partialled out. Executive functioning was strongly related to all IQ variables in the DLD group and particularly related to Verbal IQ in the HAD group. Although there was a relationship in the HAD group between executive functioning and adaptive functioning, as well as between executive functioning and autistic symptomatology, these relationships were generally no longer significant in the HAD group after the variance due to Verbal IQ was accounted for. The results are interpreted to indicate that although impaired executive functioning is a commonly associated feature of autism, it is not universal in autism and is unlikely to cause autistic behaviors or deficits in adaptive function.

Young children with Velo-Cardio-Facial syndrome (CATCH-22). Psychological and language phenotypes.

This is the first clinical description of a detailed psychological, speech, and language phenotype of four young children (< 5 years) with Velo-Cardio-Facial syndrome (VCFS) due to a deletion on chromosome 22 (22q11.2). The reported elevated risk of developing schizophrenia or bipolar disorder in adolescence for individuals with this chromosomal deletion led us to examine the psychiatric and cognitive status of young children with VCFS. Our observations suggest a phenotype comprised of a borderline to mildly retarded level of intellectual functioning, a language delay, a general deficit in social initiation, difficulties with attention/concentration, and a perturbed train of thought.

Subgroups of children with autism by cluster analysis: a longitudinal examination.

OBJECTIVES: A hierarchical cluster analysis was conducted using a sample of 138 school-age children with autism. The objective was to examine (1) the characteristics of resulting subgroups, (2) the relationship of these subgroups to subgroups of the same children determined at preschool age, and (3) preschool variables that best predicted school-age functioning. METHOD: Ninety-five cases were analyzed. RESULTS: Findings support the presence of 2 subgroups marked by different levels of social, language, and nonverbal ability, with the higher group showing essentially normal cognitive and behavioral scores. The relationship of high- and low-functioning subgroup membership to levels of functioning at preschool age was highly significant. CONCLUSIONS: School-age functioning was strongly predicted by preschool cognitive functioning but was not strongly predicted by preschool social abnormality or severity of autistic symptoms. The differential outcome of the 2 groups shows that high IQ is necessary but not sufficient for optimal outcome in the presence of severe language impairment.

Autism: the point of view from fragile X studies.

The relationship between the fragile X syndrome (FXS) and autism is reviewed. Shortly after the FXS was first described, it was noted that certain behaviors commonly found in afflicted individuals resemble certain features of autism. Research concerning a possible relationship between these conditions is summarized. The outcome of this research indicates that FXS is not a common cause of autism, although the number of individuals with FXS who meet diagnostic criteria for autism is higher than can be accounted for by chance. The major focus of this paper highlights that FXS is a well-defined neurogenetic disease that includes a cognitive behavioral phenotype, and has both a known biological cause and an increasing well-delineated pathogenesis. Autism is a behaviorally defined syndrome whose syndromic boundaries and biological causes are not known. These profound differences complicate comparisons and causal discussions. However, the behavioral neurogenetic information available about FXS suggests certain pathways for future research directed at elucidating the syndrome of autism.

Plasma oxytocin levels in autistic children.

BACKGROUND: Social impairments are central to the syndrome of autism. The neuropeptide oxytocin (OT) has been implicated in the regulation of social behavior in animals but has not yet been examined in autistic subjects. METHODS: To determine whether autistic children have abnormalities in OT, midday plasma samples from 29 autistic and 30 age-matched normal children, all prepubertal, were analyzed by radioimmunoassay for levels of OT. RESULTS: Despite individual variability and overlapping group distributions, the autistic group had significantly lower plasma OT levels than the normal group. OT increased with age in the normal but not the autistic children. Elevated OT was associated with higher scores on social and developmental measures for the normal children, but was associated with lower scores for the autistic children. These relationships were strongest in a subset of autistic children identified as aloof. CONCLUSIONS: Although making inferences to central OT functioning from peripheral measurement is difficult, the data suggest that OT abnormalities may exist in autism, and that more direct investigation of central nervous system OT function is warranted.

Diagnosis and classification in autism.

This study compared four systems for the diagnosis of autism (DSM-III, DSM-III-R, DSM-IV, and ICD-10) with two empirically derived taxa of autism, and with three social subgroups of autism (Aloof, Passive, and Active-but-Odd) in 194 preschool children with salient social impairment. There were significant behavior and IQ differences between autistic and other-PDD groups for all four diagnostic systems, and a significant association was found (a) for Taxon B, diagnoses of autism, and the Aloof subgroup, and (b) for Taxon A, other-PDD, and the Active-but-Odd subgroup. Findings offer support for two major overlapping continua within idiopathic Pervasive Developmental Disorder.

Social initiations by autistic children to adults and other children.

Social initiations made by autistic and verbal-matched retarded children were recorded in two naturalistic situations. Frequencies of initiation to adults did not differ between groups, but the retarded children initiated much more frequently to peers. Most interactions for both groups were positive, but the autistic children engaged in more ritualized, and the retarded children more playful, initiations. The autistic children monitored the social environment more when forced into proximity with peers, whereas the retarded children initiated more in the unstructured situation. Autistic initiation to peers was unrelated to severity of autism, but was related to cognitive skills, including vocabulary and comprehension of affect, whereas retarded children's initiations were unrelated to cognitive level. Results are discussed in terms of the differences between adults and children as social stimuli, prerequisite skills for initiation to peers, and the relationship between social cognition and social behavior. It is suggested that autistic and retarded children differ in the quantity of their initiations to peers, and the quality of their initiations to adults, and that initiations to peers may be a particularly useful index of social development in autistic children. Results confirm the need of autistic children for highly structured social environments, and suggest an important role for the remediation of specific cognitive skills such as comprehension of others' affects.

Is there a need for observationally based assessment of affective symptomatology in child and adolescent psychiatry?

There is growing dissatisfaction with current methods for rating affective symptoms in child and adolescent psychiatry. The need for additional reliable methods of evaluating mood disorders is significant. This annotation reviews the relative limitations of self-report and interview assessment techniques as contrasted with observationally based rating scales which offer additional advantages for assessment.

Digital rectal examination, serum prostate specific antigen, and prostatic ultrasound: how effective is this diagnostic triad?

Ninety-nine of 105 consecutive men who underwent transrectal prostatic ultrasound (TRUS) at Highland Park Hospital had the results correlated with digital rectal examination (DRE), serum prostate specific antigen (PSA), and biopsy results. Ninety-six cases had evaluable ultrasound studies. Thirty-two of the 99 who underwent biopsy had primary carcinoma of the prostate. Prostate volume, predicted PSA, a ratio of observed/predicted PSA, and Gleason score were examined. There was no correlation between age and prostate volume, volume and the presence of carcinoma, or PSA and Gleason score. Thirty-one point six percent of the abnormal DREs, 36.6% of the abnormal TRUSs, and 40.6% of the elevated PSAs occurred in men with prostatic carcinoma (PCa). If PSA was normal (less than or equal to 4.0 ng/ml) and either DRE or TRUS was abnormal, then the risk of carcinoma was 2.9%. If PSA was elevated, regardless of the other two tests, the risk of finding PCa was at least 38%. If all three tests were abnormal, the risk of carcinoma was 38% in our series and 68% in a meta-analysis. Many men with PSA values between 4 and 10 ng/ml have benign biopsies. However, close future follow-up with consideration of repeat biopsy should be strongly considered.

Adolescent adjustment to chronic physical disorders--I. Comparing neurological and non-neurological conditions.

Early research on child adjustment to chronic illness assumed that each condition had a unique impact. Recently researchers have suggested that all chronic conditions influence adjustment in similar ways. To compare these models, data were collected on 165 adolescents having chronic conditions with and without brain involvement, and 49 healthy controls. Adolescents with brain-based conditions had more behaviour problems, less autonomous functioning and poorer school achievement. Children with conditions having no brain involvement differed from controls only in reporting less work experience and having lower math achievement scores. These findings support a modified perspective that involves both general factors and effects specific to brain-based conditions.

An observationally based rating scale for affective symptomatology in child psychiatry.

There is growing dissatisfaction with current methods for rating affective symptoms in children. We report findings from a preliminary psychometric study of an alternative approach, that of direct observational ratings. The Emotional Disorders Rating Scale (EDRS) is an observation-based instrument containing 59 items divided into eight subscales. The results of this study indicate that measurement of nonverbal components of affective symptoms in children is feasible. Interrater reliability and internal consistency of the EDRS subscales were high. The EDRS also has potential as a measurement of state-related changes in affective behavior and as a technique for examining treatment response.

A case report of naltrexone treatment of self-injury and social withdrawal in autism.

The endogenous opiate release theory of self-injurious behavior (SIB) was investigated through double-blind placebo-controlled administration of naltrexone hydrochloride (Trexan) to a 14-year-old autistic and mentally retarded male for treatment of severe SIB. Results yielded a marked decrease in SIB during two phases of active drug treatment, though SIB did not revert to originally observed placebo levels during a second placebo phase. An increase in social relatedness also was observed during phases of active drug treatment. Opiate theories of self-injury and the possible interrelationship of self-injury with pituitary-adrenal arousal and with social relatedness are discussed.

Social relatedness and autism: current research, issues, directions.

Social relatedness has recently become a primary focus of investigators in the field of autism. This shift to regarding disturbances in social relatedness as one of the defining manifestations of the disorder marks the movement of research on autistic disorder back to its origins, when Kanner first noted the "social and affective" symptoms of autism as pathognomonic. Currently, social impairment in autism is viewed as more pervasively characteristic of the disorder than any other single symptom. Further, there has been a recent proliferation of research designed to document the nature of social deficit in autism, and whether it is primarily affective, communicative, or cognitive in nature, or involves some combination of these three variables. This review summarizes recent research focusing on social relatedness in autism and discusses the implications of these findings.

Screening strategies to inhibit the spread of AIDS.

In this paper we explore the costs and benefits of screening programs for the human immunodeficiency virus (HIV). Because of the low prevalence rate of the virus among the general population, the cost per detected case of a program to screen the population at large is very high. We show how this cost changes with the prevalence rate, and how screening high risk groups reduces the cost per detected case. Screening has little point, however, unless there are follow-up activities to reduce the continued spread of the virus. To this end, we present a modeling framework for determination of optimal policy alternatives after screening.