Challenging behaviour in students with intellectual disabilities: the role of individual and classmates' communication skills.

BACKGROUND: Children and adolescents with intellectual disabilities (ID) are at increased risk of developing challenging behaviour. Challenging behaviour may be partially explained by low individual communicative competences. However, communication involves at least two partners, thus outcomes may also vary according to each interaction partners' abilities. We therefore investigated the degree to which the interplay between individual and classmates' communication skills predicts changes in challenging behaviour among students with ID. METHODS: This study used a longitudinal design with two measurement points across one school year. Challenging behaviour and communication skills were measured by teacher reports in 1125 students with ID attending special needs schools. Applying a multilevel approach, we investigated (1) whether higher individual communication skills at the first measurement were related to a subsequent decrease in challenging behaviour and (2) whether this effect was moderated by classmates' levels of communication skills. In addition, we examined (3) if classroom communication skills were indirectly related to a decrease in challenging behaviour by influencing individual communicative abilities. RESULTS: Higher individual communication skills at the first measurement were significantly related to a decrease in general challenging behaviour over the school year. This effect was not moderated by classroom-level communication skills. However, classmates' communication skills exerted an indirect influence by enhancing individual communicative abilities. Further analyses suggested classroom contextual effects related to a decrease in several sub-domains of challenging behaviour. CONCLUSIONS: The study results suggest that both individual communicative competences and those of the classroom context are relevant to understanding challenging behaviour development in ID. Perspectives for counteracting such behaviour in light of the present findings are discussed.

Genotypic and phenotypic distinctness of restored and indigenous populations of Pimpinella saxifraga L. 8 or more years after restoration.

The recovery of altered or damaged ecosystems demands large-scale reintroductions of seeds. In the past, ecological restoration in Germany was carried out with non-local seeds of naturally occurring species. We here analysed whether the genetic pattern of the introduced non-local seeds (R = restored) of Pimpinella saxifraga are still detectable several years after application and whether the phenotype differs from that of the regional gene pool (I = indigenous) of the species. We collected material from individuals of R and I sites, conducted a common garden experiment and tested for genetic, morphological and phenotypic differences. In a cutting experiment we investigate treatment effects on indigenous and restored populations. At all investigated sites we only found P. saxifraga individuals with comparatively similar genome sizes. The population genetic analysis revealed two large and quite distinct molecular clusters, separating indigenous and restored individuals along the first axis. None of the vegetative, but two of the reproductive fitness parameters differed between individuals of the R and I sites. Cutting always had a significant influence on all analysed vegetative and reproductive fitness parameters, regardless of the individuals' origin. The effects of mowing always mask origin-specific characteristics, which then disappear. Genotypic coexistence reduces the availability of niches for the local genotype and may eventually lead to genotypic competition or introgression. We therefore recommend not to use non-local genotypes of this species in the region. Instead, we recommend using the genetically diverse local genotypes of P. saxifraga for restoration purposes.

Physical and structural characterisation of starch/polyester blends with tartaric acid.

Starch/PBAT blends were produced by reactive extrusion with tartaric acid (TA) as an additive. The effects of TA, glycerol and starch+PBAT on the mechanical, optical and structural properties of the films were evaluated, with formulations based in a constrained mixture design. Tartaric acid acts as a compatibiliser and promotes the acid hydrolysis of starch chains. These two functions explain the observed film resistance and opacity. TA reduced the weight loss in water. Scanning electron microscopy (SEM) images showed that TA reduces the interfacial tension between the polymeric phases, resulting in more homogeneous films. Nuclear magnetic resonance ((13)C CPMAS) and Fourier transform infrared spectroscopy (FT-IR) suggest that tartaric acid is able to react with the hydroxyl groups of the starch by esterification/transesterification reactions, confirming its role as a compatibiliser. The addition of TA results in materials with better properties that are suitable for use in food packaging.

Mixture design applied for the study of the tartaric acid effect on starch/polyester films.

Tartaric acid (TA), a dicarboxylic acid, can act as a compatibiliser in starch/polyester blends. A mixture design was proposed to evaluate the effect of TA on the properties of starch/poly (butylene adipate co-terephthalate) (PBAT) blown films plasticised with glycerol. The interaction between the starch/PBAT and the TA has a positive effect on the tensile strength and puncture force. Additionally, greater proportions of TA increased Young's modulus. The starch+PBAT/TA and Gly/TA interactions contributed to a reduction in the water vapour permeability of the films. The inclusion of TA did not change the crystallinity of the samples. Formulations with intermediate proportions of TA (0.8 g/100 g) were shown to produce the best compatibilising effect. This was observed by DMA analysis as a consequence of the perfect equilibrium between the contributions of TA as a compatibiliser and in the acidolysis of starch, resulting in films with a tensile strength of 5.93 MPa, a possible alternative to non-biodegradable packaging.

Development of biodegradable flexible films of starch and poly(lactic acid) plasticized with adipate or citrate esters.

Biodegradable films were produced from blends contained a high amount of thermoplastic starch (TPS) and poly(lactic acid) (PLA) plasticized with different adipate or citrate esters. It was not possible to obtain pellets for the production of films using only glycerol as a plasticizer. The plasticization of the PLA with the esters and mixture stages added through extrusion was critical to achieve a blend capable of producing films by blow extrusion. Adipate esters were the most effective plasticizers because they interacted best with the PLA and yielded films with appropriate mechanical properties.

Influence of the simultaneous addition of bentonite and cellulose fibers on the mechanical and barrier properties of starch composite-films.

The addition of nanoclay or cellulose fibers has been presented in the literature as a suitable alternative for reinforcing starch films. The aim of the present work was to evaluate the effect of the simultaneous incorporation of nanoclay (bentonite) and cellulose fibers on the mechanical and water barrier properties of the resultant composite-films. Films were prepared by casting with 3% in weight of cassava starch, using glycerol as plasticizer (0.30 g per g of starch), cellulose fibers at a concentration of 0.30 g of fibers per g of starch and nanoclay (0.05 g clay per g starch and 0.10 g clay per g starch). The addition of cellulose fibers and nanoclay increased the tensile strength of the films 8.5 times and the Young modulus 24 times but reduced the elongation capacity 14 times. The water barrier properties of the composite-films to which bentonite and cellulose fibers were added were approximately 60% inferior to those of starch films. Diffractograms showed that the nanoclay was intercalated in the polymeric matrix. These results indicate that the simultaneous addition of bentonite and cellulose fibers is a suitable alternative to increase the tensile strength of the films and decrease their water vapor permeabilities.

Different cue weights at the same place.

The visual system uses multiple cues to estimate properties of interest. Since the errors in the estimates from different cues for the same property are generally different, a weighted average of the cues provides a better overall estimate. The most precise estimate is found when each cue's weight is proportional to its reliability. We here show that the weights given to cues for surface slant can differ between two transparent surfaces that are at the same location at the same time. Thus the weights must be assigned separately for each structure, rather than for each location.

Living up to optimal expectations.

Natural visual scenes contain several independent sources of information (cues) about a single property such as slant. It is widely assumed that the visual system processes such cues separately and then combines them with an averaging operation that takes the reliabilities of the individual cues into account. Does that mean that people lose access to information about inconsistencies between the cues, or are all inconsistencies revealed in a distorted surface appearance? To find out, we let observers match the slant and appearance of a simulated test surface to those of an identical, simultaneously visible, simulated reference surface and analyzed the variability in the settings. We also let observers match surfaces under conditions that were manipulated in ways that were expected to favor certain cues (monocular or binocular) or to selectively disrupt certain comparisons between the surfaces (slant or structure). The patterns in the variability between the settings were consistent with predictions based on the use of all available information. We argue that information about discrepancies is only "lost" during cue combination if there is no benefit in retaining the information.

Pathology associated with sporadic Parkinson's disease--where does it end?

Parkinson's disease (PD) is a multisystem disorder in which predisposed neuronal types in specific regions of the human peripheral, enteric, and central nervous systems become progressively involved. A staging procedure for the PD-related inclusion body pathology (i.e., Lewy neurites and Lewy bodies) in the brain proposes that the pathological process begins at two sites and progresses in a topographically predictable sequence in 6 stages. During stages 1-2, the inclusion body pathology remains confined to the medulla oblongata, pontine tegmentum, and anterior olfactory structures. In stages 3-4, the basal mid- and forebrain become the focus of the pathology and the illness reaches its symptomatic phase. In the final stages 5-6, the pathological process is seen in the association areas and primary fields of the neocortex. To date, we have staged a total of 301 autopsy cases, including 106 cases with incidental pathology and 176 clinically diagnosed PD cases. In addition, 163 age-matched controls were examined. 19 of the 301 cases with PD-related pathology displayed a pathological distribution pattern of Lewy neurites and Lewy bodies that diverged from the staging scheme described above. In these cases, olfactory structures and the amygdala were predominantly involved in the virtual absence of brain stem pathology. Most of the divergent cases (17/19) had advanced concomitant Alzheimer's disease-related neurofibrillary changes (stages IV-VI).

The origin of four squirrel monkey cell lines established by karyotype analysis.

The squirrel monkey is a neotropical primate genus which is widely used in biomedical research but includes individual species and subspecies that respond differently to experimental perturbations. GTG-banding patterns of chromosomes 15 and 16, which are distinct among different squirrel monkey species and subspecies, were used to determine the origin of three lung fibroblast cell lines from squirrel monkeys of unknown genetic background (DPSO 114/74, SqMkLu/68, and 7603830) and to confirm the origin of a lymphoblast cell line (GSML) recently established from Guyanese squirrel monkey. DPSO 114/74 cells are from Peruvian squirrel monkey, SqMkLu/68 cells are Bolivian squirrel monkey, and 7603830 cells are from a Peruvian/Bolivian hybrid. Chromosome analysis of GSML cells confirmed that they are from Guyanese squirrel monkey.

Partial trisomy 7p defined by analysis of a complex chromosome rearrangement using a BAC clone panel.

PURPOSE: To illustrate the use of bacterial artificial chromosome (BAC) clone panels for molecular cytogenetic analysis of complex chromosome rearrangements (CCRs). METHODS: High resolution cytogenetics followed by fluorescence in situ hybridization (FISH) analysis using chromosome band-specific BAC probes, in addition to commercially available probes. RESULTS: High resolution cytogenetics in conjunction with FISH using commercially available probes proved inadequate to resolve problems in characterizing a balanced CCR in the mother of a patient who had inherited an unbalanced form of the CCR. Accurate interpretation of the CCR and the unbalanced rearrangement in the patient as trisomy 7p12.2-->p21.3 was accomplished only through use of the BAC clone panel. CONCLUSION: Use of BAC clone panels can enhance the power of FISH analysis in defining chromosome rearrangements that cannot be resolved by high resolution chromosome analysis.

DNA hypomethylation and unusual chromosome instability in cell lines from ICF syndrome patients.

The ICF syndrome (immunodeficiency, centromeric region instability, facial anomalies) is a unique DNA methylation deficiency disease diagnosed by an extraordinary collection of chromosomal anomalies specifically in the vicinity of the centromeres of chromosomes 1 and 16 (Chr1 and Chr16) in mitogen-stimulated lymphocytes. These aberrations include decondensation of centromere-adjacent (qh) heterochromatin, multiradial chromosomes with up to 12 arms, and whole-arm deletions. We demonstrate that lymphoblastoid cell lines from two ICF patients exhibit these Chr1 and Chr16 anomalies in 61% of the cells and continuously generate 1qh or 16qh breaks. No other consistent chromosomal abnormality was seen except for various telomeric associations, which had not been previously noted in ICF cells. Surprisingly, multiradials composed of arms of both Chr1 and Chr16 were favored over homologous associations and cells containing multiradials with 3 or >4 arms almost always displayed losses or gains of Chr1 or Chr16 arms from the metaphase. Our results suggest that decondensation of 1qh and 16qh often leads to unresolved Holliday junctions, chromosome breakage, arm missegregation, and the formation of multiradials that may yield more stable chromosomal abnormalities, such as translocations. These cell lines maintained the abnormal hypomethylation in 1qh and 16qh seen in ICF tissues. The ICF-specific hypomethylation occurs in only a small percentage of the genome, e.g., ICF brain DNA had 7% less 5-methylcytosine than normal brain DNA. The ICF lymphoblastoid cell lines, therefore, retain not only the ICF-specific pattern of chromosome rearrangements, but also of targeted DNA hypomethylation. This hypomethylation of heterochromatic DNA sequences is seen in many cancers and may predispose to chromosome rearrangements in cancer as well as in ICF.

Seasonal changes in astrocytes parallel neuronal plasticity in the song control area HVc of the canary.

In the song control area HVc of the canary, intercellular dye-coupling among astrocytes was studied by intracellular injection of neurobiotin into identified single astrocytes. Injection of individual astrocytes into acute slices resulted in dye spread to neighboring astrocytes, covering a sphere of up to 1 mm in diameter. The astrocytic nature of the dye-coupled cells was verified by double labeling of neurobiotin-filled cells with antisera for the astrocytic filament proteins GFAP or vimentin. The similarity in the number of dye-coupled cells and the total number of astrocytes labeled by immunocytochemical markers indicate that dye-coupling is specific for astrocytes and labels almost the entire local astrocytic population. Within the major nucleus for vocal control (HVc), approximately 25% more astroglial cells were present than in the surrounding forebrain tissue. There is no apparent hindrance of dye spread at the border of the HVc. The density of dye-coupled astrocytes and the expression of cytoskeletal filament proteins differed markedly between the reproductive period in spring and the quiescent period in autumn. While vimentin is the major astroglial filament in autumn, GFAP is strongly expressed in spring. The density of dye-coupled astrocytes reveals a marked increase in the reproductive period, followed by a reduction in autumn. The data indicate that the astrocytic population in the avian forebrain undergoes significant changes coincident with the known functional changes in the vocal control nuclei during periods of song production.

Adrenal insufficiency in Smith-Lemli-Opitz syndrome.

We describe three unrelated patients with adrenal insufficiency and RSH or Smith-Lemli-Opitz syndrome (SLOS), a disorder due to deficient synthesis of cholesterol. These patients presented with hyponatremia, hyperkalemia, and decreased aldosterone-to-renin ratio, which is a sensitive measure of the renin-aldosterone axis. All patients had profound serum total cholesterol deficiency (14-31 mg/dl) and marked elevation of 7-dehydrocholesterol (10-45 mg/ dl). Two patients were newborn infants with 46, XY karyotypes and complete failure to masculinize; one of these patients also had cortisol deficiency. Both patients died within 10 days of birth of cardiopulmonary complications while on adrenal replacement therapy. The third patient diagnosed with SLOS at birth presented at age 7months with fever and diarrhea and was noted to have profound hyponatremia. This patient is maintaining normal serum electrolytes on mineralocorticoid replacement. We conclude that adrenal insufficiency may be a previously undetected and treatable manifestation in SLOS. We hypothesize that deficiency of cholesterol, an adrenal hormone precursor, may lead to insufficient synthesis of adrenal steroid hormones.

1p microdeletion in sibs with minimal phenotypic manifestations.

We report on two sibs with a paracentric inversion of chromosome 1 [inv(1)(p22.3p34.1)] and a small deletion of the same chromosome (p34.1-->p34.3). They presented with learning disabilities and disturbed conduct but lacked the more severe manifestations usually associated with autosomal chromosome deletion. Born to an alcoholic mother and later placed in foster care because of abuse and neglect, the behavior abnormalities they present are likely to be associated with their traumatic postnatal experience. Microscopic deletions without significant morphological phenotypic expression have been described but are rarely reported. Most reported cases of interstitial deletion of 1p had associated malformations and psychomotor retardation. These sibs may represent the first evidence that deletion of 1p34.1-->1p34.3 may have little impact on the phenotype.

Prenatal detection of de novo duplication of the short arm of chromosome 18 confirmed by fluorescence in situ hybridization (FISH).

We present a patient with developmental delay, minor anomalies, and duplication 18p confirmed by fluorescence in situ hybridization with whole chromosome 18 painting probe (Oncor p5218). Our observation confirms the findings of other investigators that duplication 18p is not associated with major malformations.

Tissue plasminogen activator mediates reverse occlusion plasticity in visual cortex.

Preventing visual input to one eye (monocular deprivation) in early postnatal development reduces cortical responses to stimulation of the deprived eye, with a significant loss of thalamocortical connections. These effects are reversible by opening the deprived eye and closing the previously open eye (reverse occlusion). We show that intracortical blockade of tissue plasminogen activator or plasmin selectively prevents recovery of cortical function and thalamic neuron size during reverse occlusion, without affecting the monocular deprivation response. Therefore, a proteolytic cascade consisting of plasmin generated by tissue plasminogen activator may selectively mediate reverse-occlusion-induced cortical plasticity, perhaps via structural remodeling of axons.

Critical period-dependent reduction of the permissiveness of cat visual cortex tissue for neuronal adhesion and neurite growth.

During postnatal development, the visual cortex undergoes an experience-dependent refinement of its circuitry. This process includes synapse formation, as well as synapse elimination. Both mechanisms appear to be restricted to a limited 'critical period' which lasts for approximately 2 months in cats. We tested whether the termination of the critical period for cortical malleability is paralleled by changes in the growth permissiveness of the tissue. These changes may inhibit progressive reorganization of functional circuitries mediated by axon growth. Embryonic cortical neurons were cultured on unfixed cryostat sections of the visual cortex obtained from cats aged 2-50 weeks. After 2-3 days in vitro the distribution of viable cells and the percentage of neurite-bearing cells were determined and analysed with respect to the developmental age and subdivisions of the underlying tissue substrate. It was shown that cell adhesion and neurite formation are correlated with the developmental age of the substrate tissue and the time period of myelination. While embryonic neurons adhered and survived on grey and white matter tissue from 2- and 4-week-old kittens, there was a significant reduction in cell adhesion on the myelinated white matter regions of the tissue sections of older animals. Quantitative analyses showed that neurite formation by cultured neurons also became successively impaired on grey and white matter areas of tissue substrates, corresponding to the time course of the critical period for cortical malleability. On grey matter tissue this effect was most pronounced between the second and sixth postnatal weeks. The effects were not antagonized by coating the substrate sections with the growth-promoting molecule laminin. It is therefore proposed that neurite growth-inhibiting factors, most probably associated with central nervous system myelin, are gradually expressed postnatally and may contribute to the termination of the critical period in the visual cortex of cats.