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Developmental disorders in embryos of the frog Xenopus laevis induced by chloroacetanilide herbicides and their degradation products.

Pesticides are known to transform in the environment, but so far the study of their effects in the environment has concentrated on the parent compounds, thereby neglecting the effects of the degradation products. The embryotoxic, developmental, and teratogenic effects of chloroacetanilide herbicides and their environmentally stable aniline degradation products were investigated in this study in view of the massive application of alachlor and metolachlor. Embryos at midblastula to early gastrula stages of a locally abundant African clawed frog Xenopus laevis were used as test organisms. The embryos were exposed to the test chemicals for 96 h in each experiment. Alachlor is more embryotoxic (the concentration causing 50% embryo lethality, 96-h LC50 = 23 microM [6.1 mg/L]) and teratogenic (teratogenic index [TI] = 1.7) than metolachlor (96-h LC50 = 48 microM [13.6 mg/L], TI = 0.2). The degradation products of alachlor and metolachlor, respectively, 2,6-diethylaniline (96-h LC50 = 13 microM [19.4 mg/L], TI = 2.1) and 2-ethyl-6-methyaniline (96-h LC50 = 509 microM [68.8 mg/L], TI = 2.7), are less embryotoxic but more teratogenic than their parent compounds. The most common teratogenic effects observed were edema for alachlor as opposed to axial flexures and eye abnormalities for 2,6-diethylaniline and 2-ethyl-6-methylaniline. Metolachlor is found to be an example of a nonteratogenic herbicide that upon degradation loses toxicity but gains teratogenicity, and both the herbicides, metolachlor and alachlor, are potential sources of teratogenic transformation products.

Acetamides↗

[Delayed visual maturation--a differential diagnostic challenge. A follow-up study of 13 children with delayed visual development with or without other developmental disorders].

Early visual impairment represents several diagnostic possibilities from specific delayed visual maturation (type 1) with an excellent prognosis to more complex conditions with other ocular or neurological signs (type 2-4). Visual attention and interaction has been an interesting field of study in the interaction between biologically pre-programmed neonatal competencies and social facilitation. From these studies we can probably learn more about ((cloudy)) diagnoses such as cortical visual impairment, attention deficit hyperactivity disorder and autism. Investigations and follow-up of 13 infants who did not show any visual interest at 6 - 12 weeks old are presented, along with proposals for the clinical management of these problems.

Developmental Disabilities↗

[Evaluation of a tool for developmental disorder screening in 4-year-old children].

With the aim of helping physicians working in a "Mother and Infant Protection Service" (PMI) in their mission of children's development difficulties screening, authors tried to assess performances of a clinical tool including parental informations and standardized tests. The whole four years old children going at school in a canton of Calvados department were independently examined by a PMI doctor using the tool to be estimated and by a specialized service working from a beforehand established protocol. For the language disorders on the one hand and the adaptation on the other hand, this evaluation shows a significant correlation between the PMI screening and the specialists one's: the sensitivity of the PMI examination is about 70% for those two types of difficulties with a positive predictive value respectively 28% and 57%. However the tool appears less reliable for the psychomotor disorders screening: only one quarter of the children who require a specialized investigation about these problems have been detected by the PMI screening. A filing and a selection of the questionnaire items should permit to improve the efficiency of this tool.

Child, Preschool↗

[Bone diseases: review and classification of congenital developmental disorders].

There is no complete and satisfactory system of classification for constitutional bone diseases available at present. A combination of precise phenotypical description and genetical analysis has been shown, however, to increase our understanding of the basic defects and to allow an etiological classification of an increasing number of bone diseases. Examples are given to illustrate the usefulness of Mendelian analysis (autosomal dominant and recessive inheritance, X-linkage), microcytogenetics, cellular pathology, enzyme biochemistry, analysis of the gene products, and DNA analysis. The phenotype cannot be understood without knowledge of its genetic basis, but knowledge of the genetic basis laid down in the DNA is only useful in connection with knowledge of the phenotype, which cannot be derived from knowledge of the DNA.

Bone Diseases, Developmental↗

[Prenatal and early postnatal motor development and its importance in recognizing developmental disorders].

The normal central nervous system is characterized by both activity and reactivity. Under normal circumstances the former leads the latter. In abnormal conditions reactivity may predominate, usually in the form of reflexes and abnormal postural reactions. Ultrasound registration shows that the first spontaneous motor movements can be seen in the seventh to eighth gestational week. Movement patterns develop fast, and in mid-pregnancy all patterns are observed that can be found in the term newborn baby. During the second half of pregnancy movement patterns are refined: the first differentiation leading to variable and fluent movements. The intrauterine movements are qualitatively more or less similar to those seen in normal preterm babies, the main difference being that the latter as to counteract gravity forces to a greater extent. Qualitative changes of the movement patterns signal deteriorating intrauterine conditions. Stereotyped quality of movement can be a sign of abnormal development. During infancy normal development is characterized by great variability in performance, developmental sequences and relationships. Stereotype performance and strong relationship between the various motor functions, reactions and reflexes should arouse the suspicion that there may be a disturbance in development.

Child, Preschool↗

[Ring chromosome 21 as a cause of developmental disorder. A case report from the practice of child psychiatry].

Ring chromosome 21 is a very rare chromosomal abnormality known to cause a great variety of clinical findings. Persons with ring chromosome 21 can be intellectually and phenotypically normal, but this abnormality is found more often in persons with dysmorphic features, malformations and mental retardation. Ring chromosome 21 is also encountered as the only chromosomal abnormality in individuals with Down syndrome. We describe a four year old girl with ring chromosome 21 (karyotype 46,XX/46,XX,-21, +r(21)), who was examined in a department of child psychiatry because of delayed development. The child had serious speech and language problems, slightly dysmorphic features and bilateral hip-joint dysplasia.

Child Psychiatry↗

The roles of cilia in developmental disorders and disease.

Cilia are highly conserved organelles that have diverse motility and sensory functions. Recent discoveries have revealed that cilia also have crucial roles in cell signaling pathways and in maintaining cellular homeostasis. As such, defects in cilia formation or function have profound effects on the development of body pattern and the physiology of multiple organ systems. By categorizing syndromes that are due to cilia dysfunction in humans and from studies in vertebrate model organisms, molecular pathways that intersect with cilia formation and function have come to light. Here, we summarize an emerging view that in order to understand some complex developmental pathways and disease etiologies, one must consider the molecular functions performed by cilia.

Animals↗

The role of genomic imprinting in human developmental disorders: lessons from Prader-Willi syndrome.

Normal human development involves a delicate interplay of gene expression in specific tissues at narrow windows of time. Temporally and spatially regulated gene expression is controlled both by gene-specific factors and chromatin-specific factors. Genomic imprinting is the expression of specific genes primarily from only one allele at particular times during development, and is one mechanism implicated in the intricate control of gene expression. Two human genetic disorders, Prader-Willi syndrome (PWS, MIM 176270) and Angelman syndrome (AS, MIM 105830), result from rearrangements of chromosome 15q11-q13, an imprinted region of the human genome. Despite their rarity, disorders such as PWS and AS can give focused insight into the role of genomic imprinting and imprinted genes in human development.

Alleles↗

Stability and change among high-functioning children with pervasive developmental disorders: a 2-year outcome study.

This study prospectively compared the 2-year outcome of children diagnosed with autism or Asperger syndrome at age 6-8 years in terms of symptoms from the Autism Diagnostic Interview. Significant differences were seen in the three-domain summary scores of social interaction, communication, and repetitive activities, with the Asperger syndrome group demonstrating fewer and/or less severe symptoms at both times. There was a trend for the trajectories to come together over time on the socialization and communication domains, but not the repetitive activities domain. Differences were not attributable to IQ. Analysis of individual items indicated that the autism group improved over time on seven items and showed increased symptom severity on three items. On the other hand, the Asperger syndrome group improved on only two items and showed increased symptom severity on six items. Results suggest that the two PDD subtypes represent similar developmental trajectories, although the Asperger syndrome group maintains its advantage. Educational and clinical implications of the results are discussed.

Asperger Syndrome↗

Developmental disorders of skin potential responses in mentally retarded children during nocturnal sleep.

Skin potential responses (SPRs) of 89 mentally retarded children were studied during their nocturnal sleep. Forty-three out of the 89 subjects showed more SPRs (type A) during NREM sleep than in REM sleep. The opposite was observed in 10 cases (type C), and 4 had evenly distributed SPRs during both sleep phases (type B). The remaining 32 subjects had mixed types AB (n = 19), AC (n = 6) or BC (n = 7). Types B and C (including the mixed type) were observed more frequently for subjects with low developmental quotient (DQ) and abnormal clinical EEGs than for those with high DQ and normal clinical EEGs. Since it has been well established that normal subjects of 3 months and over exhibit exclusively type A, SPRs may be used as an additional tool for the diagnostic assessment of mental retardation in early infancy.

Adolescent↗

Repetitive and stereotyped behaviours in pervasive developmental disorders.

BACKGROUND: Repetitive and stereotyped behaviours are a heterogeneous group of behaviours present in many neuropsychiatric disorders. Despite their core significance in PDD, it is not clear whether there are distinct groups of these behaviours with different specificity to autism. METHODS: A two-factor model of the repetitive behaviours, namely sensory/motor (lower-order) and cognitive rigidity (higher-order), was conceptualised. The model's goodness of fit to the data was examined in a clinic population of children with PDD, with and without mental retardation, and of those with only mental retardation (MR). RESULTS: Subjects with PDD had higher rates of all repetitive behaviours compared to those with MR only. The existence of two independent 'lower-order' and 'higher-order' sub-groups of the repetitive behaviours was confirmed only in the MR group. The lower-order behaviours appear to be associated more with global developmental problems, whereas the higher-order behaviours were significantly associated with ruminations in the PDD group. CONCLUSIONS: This study suggests that there may be two distinct sub-groups of repetitive behaviours whereby the sensory and motor repetitive behaviours are generally associated with lower developmental age and less specific to the autistic syndrome whereas the 'higher-order' behaviours may be a more 'autism specific' feature. The co-occurrence of the lower- and higher-order behaviours in PDD might reflect the end result of diffuse altered neural networks in these disorders thus being a specific feature of PDD. There is a need for more systematic studies of these behaviours not only in autistic disorders but also in other neuropsychiatric disorders.

Child↗

From developmental disorder to heritable cancer: it's all in the BMP/TGF-beta family.

Transforming growth factor-beta (TGF-beta) regulates many cellular processes through complex signal-transduction pathways that have crucial roles in normal development. Disruption of these pathways can lead to a range of diseases, including cancer. Mutations in the genes that encode members of the TGF-beta pathway are involved in vascular diseases as well as gastrointestinal neoplasia. More recently, they have been implicated in Cowden syndrome, which is normally associated with mutations in the phosphatase and tensin homologue gene PTEN. Molecular studies of TGF-beta signalling are now showing why mutations in genes that encode components of this pathway result in inherited cancer and developmental diseases.

Animals↗

[The status of biological risk factors and the optimality concept in diagnosis of early childhood developmental disorders].

In a prospective study the psychomotor development up to the end of the second year of life of 409 preterm and term newborn infants was examined in order to identify which optimality score might be associated with disturbances of normal childlike development. Significant connections between 24 and 55 risk factors and the mortality could be demonstrated, but only 3 factors (sex, apgar, acidosis) exert influence on psychomotor development. The risk loading of the collective was high, not one of the children showed an optimal score. Decreased patients possessed a stronger reduced optimality than survivors. The optimality concept is not suitable for the prediction of later disturbed development of children, because the items are unspecific. The marker of hypoxia, the erythrocytic-density-test, as well as the neuron-specific enolase showed better diagnostic values than the optimality concept.

Brain Damage, Chronic↗

Overlapping submicroscopic deletions in Xq28 in two unrelated boys with developmental disorders: identification of a gene near FRAXE.

Two unrelated boys are described with delay in development and submicroscopic deletions in Xq28, near FRAXE. Molecular diagnosis to exclude the fragile X (FRAXA) syndrome used the direct probe pfxa3, together with a control probe pS8 (DXS296), against PstI restriction digests of DNA. Deletions were detected initially by the control probe pS8, which is an anonymous fragment subcloned from YAC 539, within 1 Mb distal to FRAXA. Further molecular analyses determined that the maximum size of the deletion is < 100 kb in one boy (MK) and is wholly overlapped by the deletion of up to approximately 200 kb in the other (CB). These deletions lie between the sequences detected by the probe VK21C (DXS296) and a dinucleotide repeat VK18AC (DXS295). The patient MK had only speech delay with otherwise normal development, while patient CB had global developmental delay that included speech delay. Detection of overlapping deletions in these two cases led to speculation that coding sequences of a gene(s) important in language development may be affected. Hybridization of the pS8 and VK21A probes to zooblots revealed cross-species homology. This conservation during evolution suggested that this region contains sequences with functional significance in normal development. The VK21A probe detected a 9.5-kb transcript in placenta and brain and a smaller, 2.5-kb, transcript in other tissues analyzed.

Child, Preschool↗

Neuronal migration in developmental disorders.

Normal central nervous system development is dependent on extensive cell migration. Cells born in the proliferative ventricular zone migrate radially along specialized glial processes to their final locations. In contrast, most inhibitory interneurons found in the adult mammalian cerebral cortex and some other structures migrate along a nonradial pathway and on substrates only recently defined. Defects in radial cell migration have been implicated in several distinct human syndromes in which patients often present with epilepsy and mental retardation and have characteristic cerebral abnormalities. The identification of several genes responsible for human neural cell migration defects has led to a better understanding of the cellular and molecular interactions necessary for normal migration and the pathogenesis of these disorders. The prototypic cell migration disorder in humans is type I lissencephaly. Although type 1 lissencephaly is clearly a defect in radial cell migration, recent data from two model systems (Lis1 and ARX mutant mice) indicate that a defect in non-radial cell migration also exists. Thus, the result of a LIS1 mutation appears to have broader implications than a radial cell migration defect alone. Furthermore, it is likely that the observed defect in non-radial cell migration contributes to the clinical phenotype observed in these patients. Herein we discuss the role of normal non-radial cell migration in cortical development, as well as how perturbations in both radial and nonradial migration result in developmental anomalies.

Brain Diseases↗

[Early detection of developmental disorders: the need for a new perspective].

Early detection of abnormality in young children (aged 0-7) in the Netherlands is to be organized on two levels. First, regional cooperation between child-health professionals and institutions will be stimulated in order to form a nationwide network of 'multidisciplinary teams', with the task of coordinating early detection in a specific area. These teams are to advise parents and professionals in those cases where a child's development is suspected of being 'at risk'. The second part of the program is a campaign to promote the idea of early detection among the population. The aim is to develop the 'signalizing' and diagnostic abilities of parents, teachers and child-health professionals through education and training. The subject of early detection seemed and still seems to be a focus of different interests, and of conflicts of competence between different groups and schools of professionals and different institutions. In this article some of the main conflicting issues are discussed. One of the important problems concerning early detection is the question of defining normality and abnormality. It is concluded that in the case of early detection of both somatic and psychosomatic disorder there can be no such thing as an absolute scientific rationality, as is often suggested. Theoretical frameworks underlying methods of early detection are influenced by social, cultural and historical factors, and thus form a social construction. Finally a protocol-approach is being suggested, a method that might clear some of the problems concerning the content and organizational procedures of the Dutch system for early detection.

Child↗

Regression versus no regression in the autistic disorder: developmental trajectories.

Developmental regression is a complex phenomenon which occurs in 20-49% of the autistic population. Aim of the study was to assess possible differences in the development of regressed and non-regressed autistic preschoolers. We longitudinally studied 40 autistic children (18 regressed, 22 non-regressed) aged 2-6 years. The following developmental areas were considered fundamental in the first years of life, and were assessed at ages 2, 3, 4, 5, and 6: receptive and expressive language, communicative and request modalities, play activities, and mental age. Children who regressed showed lower mean performances than those who did not regress and, in the time intervals considered, non-regressed children improved their ratings in the above mentioned variables significantly more than regressed children.

Autistic Disorder↗