Relationship dimensions of the 'Down syndrome advantage'.

BACKGROUND: Some researchers have proposed an 'advantage' for parents of children with Down syndrome over parents of children with other intellectual disabilities, especially in relation to experiencing less parenting stress. Others have maintained that these differences are an artefact of demographic and related differences. This study extends the investigation of possible differences in dimensions of parenting stress and also examines whether differences exist in maternal and child contingent responsiveness during mother-child interaction in these two groups. METHOD: Mothers of children with Down syndrome (n = 43) and undifferentiated developmental disabilities (n = 54) completed measures of children's adaptive functioning and behaviour problems, parenting stress and maternal social support. Observers rated the contingent interactions between mothers and children using the Nursing Child Assessment Teaching Scale. RESULTS: Once mother's age, education and social support as well as child adaptive functioning and behaviour problems were considered, neither parent nor child related parenting stress demonstrated an advantage for parents of children with Down syndrome. However, a 'Down syndrome advantage' was apparent for both maternal and child contingent responsiveness after accounting for maternal demographic and contextual variables and child attributes. CONCLUSIONS: Children with Down syndrome and their mothers have more positive interactions than children with other developmental disabilities, both in terms of the responsiveness of mothers and of child responses contingent on maternal behaviour. These findings suggest that both children with Down syndrome themselves and their mothers are contributing to a Down syndrome advantage.

Early childhood predictors of mothers' and fathers' relationships with adolescents with developmental disabilities.

BACKGROUND: The importance of positive parent-adolescent relationships is stressed in research on adolescents, although very little is known about this relationship when a teen has developmental disabilities (DD). We investigated the relationships of adolescents with disabilities with their mothers and their fathers in order to answer a number of questions regarding these relationships. In particular, we asked: are there differences in the relationships of mothers and fathers with their adolescent with DD? Are there early childhood predictors of the parent-teen relationship and are those based on variables that are amenable to intervention? Finally, do these predictors differ for mothers and fathers? METHODS: This study focused on the relationships of 72 mothers and 53 fathers with their 15-year-old teens with DD and their predictors from the early childhood years. Data were collected from parents through interviews and self-administered questionnaires, and from their children with disabilities through structured assessment when children were age 3 years and again at age 15 years. RESULTS: Analyses indicated that both mother-teen and father-teen relationships were predicted by earlier parenting stress. The father-teen relationship was also predicted by early behaviour problems, but this relation was mediated by parenting stress. Socio-economic status, type of disability and the child's level of functioning were not predictive of later relationships between parents and teens. Mothers and fathers did not differ significantly in their reports of perceived positive relationships with their teens. CONCLUSIONS: The findings from this study suggest two important points of potential intervention during the early intervention years. First, parenting assistance and support to reduce stress during the early childhood years can benefit both mothers and fathers. Second, helping families and children cope with and diminish problem behaviours is likely to yield multiple advantages for parents and children and deserves emphasis in early intervention and pre-school programmes.

Prevention of HIV-1 infection and preservation of CD4 function by the binding of CPFs to gp120.

Infection by human immunodeficiency virus type-1 (HIV-1) is initiated when its envelope protein, gp120, binds to its receptor, the cell surface glycoprotein CD4. Small molecules, termed N-carbomethoxycarbonyl-prolyl-phenylalanyl benzyl esters (CPFs), blocked this binding. CPFs interacted with gp120 and did not interfere with the binding of CD4 to class II major histocompatibility complex molecules. One CPF isomer, CPF(DD), preserved CD4-dependent T cell function while inhibiting HIV-1 infection of H9 tumor cells and human T cells. Although the production of viral proteins in infected T cells is unaltered by CPF(DD), this compound prevents the spread of infection in an in vitro model system.

Drug delivery using vesicles targeted to the hepatic asialoglycoprotein receptor.

We assessed the utility of liver-targeted vesicles as a drug delivery system for the treatment of liver diseases. Small, unilamellar vesicles (mean diameter, 60-80 nm) composed of dipalmitoylphosphatidylcholine, cholesterol, dipalmitoylphosphatidylglycerol and digalactosyldiacylglycerol (mol ratios, 40:40:5:15) are rapidly cleared from the blood in rats after intravenous injection. In vivo organ distribution shows that the liver is the major site of vesicle accumulation, with roughly 60-80% of the vesicle contents delivered to the liver. Isolated, perfused rat liver experiments show that the uptake is due to the hepatic asialoglycoprotein receptor, and the uptake process occurs with minimal vesicle leakage. At low doses of the vesicles, the single pass extraction by the liver is around 50%, which means that this vesicle formulation operates close to optimal efficiency as a drug delivery system to the liver. Binding of vesicles to the liver was determined to saturate at 6.5 mg total lipid/kg body weight, with a maximum steady-state turnover rate of vesicles at 37 degrees C of 79 micrograms lipid/min per kg body weight. This gives a receptor recycling time of around 80 min. We have incorporated this information into a pharmacokinetic model of vesicle distribution which quantitatively predicts the kinetics and dose dependence of vesicle uptake by the liver in vivo. This information can be used to optimize vesicle-mediated drug delivery to the liver.

Cloning of the phytases from Emericella nidulans and the thermophilic fungus Talaromyces thermophilus.

Phytases (EC 3.1.3.8) belong to the family of histidine acid phosphatases. We have cloned the phytases of the fungi Emericella nidulans and Talaromyces thermophilus. The putative enzyme encoded by the E. nidulans sequence consists of 463 amino acids and has a Mr of 51785. The protein deduced from the T. thermophilus sequence consists of 466 amino acids corresponding to a Mr of 51450. Both predicted amino acid sequences exhibited high identity (48% to 67%) to known phytases. This high level of identity allowed the modelling of all available fungal phytases based on the three-dimensional structure coordinates of the Aspergillus niger phytase. By this approach we identified 21 amino acids which are conserved in fungal phyA phytases and are part of the residues forming the substrate pocket. Furthermore, potential glycosylation sites were identified and compared between the aforementioned phytases and the A. niger phytase.

Confirmed reservations: mental travel.

When Kosslyn, Ball, and Reiser asked subjects to scan a memorized picture, they found a strong positive linear relationship between distance scanned and reaction time. However, more recent research has suggested that this result may be as much a function of the demand characteristics of the experiment as a reflection of any structural properties of the image. To further test this possibility with complex stimuli, college subjects were either presented with Kosslyn's pictorial stimuli or verbal descriptions of same in a "nonexperiment" and were asked to predict their scanning times. The subjects were able to produce high linear correlations between scanning distance and predicted scanning time. This result is consistent with a demand characteristics explanation of the correlation between distance and reaction time that is obtained in actual image-scanning studies.

Mental travel: some reservations.

Two experiments were conducted to assess the extent of potential experimental demand characteristics inherent in the image-scanning paradigm. The results of the first "mental travel" experiment that pitted verbal versus imagery coding showed that (a) the positive correlation between physical distance and reaction time was replicated, and (b) when given a choice, subjects' reaction times varied as a function of verbal codes rather than imagery. To isolate the effects due to demand constraints from those produced by mode dominance, a nonexperiment in which subjects received only a description of the image-scanning procedure was conducted. Results demonstrated that subjects were capable of predicting the reaction time results for both verbal and imagery codes. The presence of experimental demand in the image-scanning paradigm necessitates caution when structural interpretations of visual images are considered.

Role of glutathione depletion in the cytotoxicity of acetaminophen in a primary culture system of rat hepatocytes.

A primary culture system of postnatal rat hepatocytes was utilized to study the cytotoxicity of acetaminophen and the toxicological significance of glutathione (GSH) depletion. The relative time of onset and magnitude of GSH depletion, lipid peroxidation and cytotoxicity were contrasted in order to gain insight into their interrelationships. Exposure of the hepatocytes to acetaminophen resulted in time- and dose-dependent depletion of cellular GSH. The acetaminophen-induced GSH depletion and ensuing lactate dehydrogenase (LDH) leakage were quite modest and delayed in onset, in contrast to that caused by iodoacetamide (IAA) and by diethylmaleate (DEM), 2 well-known depletors of GSH. There was comparable LDH leakage, irrespective of drug treatment, when GSH levels decreased to about 20% of normal. Reduction of GSH levels below the 20% threshold by IAA treatment resulted in marked LDH leakage and loss of viability. Maximal LDH leakage in response to IAA and acetaminophen preceded maximal malondialdehyde (MDA) formation, suggesting that lipid peroxidation may be a consequence of cell damage as well as GSH depletion. IAA and DEM produced a comparable, modest accumulation of MDA, yet IAA was much more cytotoxic. These findings indicate that lipid peroxidation does not play a central role in hepatocellular injury by compounds which deplete GSH, although it may contribute to degeneration of the cell. As events in the cultured postnatal hepatocytes paralleled those reported in vivo, the system can be a useful and valid model with which to study mechanisms of chemical toxicity.

Cognitive and social functioning across adulthood: age or student status differences?

Younger adult students between 19 and 24 years of age (M = 21.3 years), older adult students between 61 and 76 years of age (M = 67.9 years), and older adult nonstudents between 62 and 76 years of age (M = 68.5 years) were assessed for health (self-ratings of physical and mental health), social functioning (self-ratings of physical and mental activity, perceived role activity level, perceived roles, locus of control, and age-norm expectations), and cognitive functioning (Wechsler Adult Intelligence Scale-Revised vocabulary and block design, and paired associate memory). Age differences were observed in self-ratings of health, social roles, intellectual performance, and memory. No student status differences were observed. The results are discussed in terms of plasticity of intellectual function and characteristics of student status in later adulthood.

Dissociations between procedural and episodic memory: effects of time and aging.

The issue of multiple memory systems is explored. Young and older adults (mean ages = 20 and 71, respectively) named pictures and were tested immediately, 1, 7, or 21 days later. Episodic memory (recognition) for pictures was significantly lower in older relative to young adults and declined systematically across all retention intervals in both age groups. In contrast, procedural memory (repetition priming in picture naming) revealed no reliable age differences. In both age groups, priming declined within the first 24 hr, but unlike recognition, there was no further decrement from 1 to 21 days. There were also within-subject dissociations: The magnitude of priming was equivalent for remembered and forgotten items, and the relation between recognition and priming across intervals was nonmonotic, revealing a reversed association. The findings were interpreted within a multiple-memory-systems framework.

Lack of cytotoxicity of ticrynafen in primary cultures of rat liver cells.

Primary cultures of hepatocytes obtained from neonatal Sprague-Dawley rats were grown in arginine-deficient, ornithine-supplemented medium to inhibit fibroblastic overgrowth and to selectively isolate relatively pure cultures of parenchymal hepatocytes. This system of primary hepatocytes was used to study the potential cytotoxicity of ticrynafen by measuring cytoplasmic enzyme leakage, cell viability,, and total protein per culture dish. Hepatic cultures were treated with the drug in concentrations ranging from 10(-3)M to 10(-6)M and for durations from 2 to 8 h. The results of the study indicate that ticrynafen was minimally toxic to the hepatocytes.

How many memory systems? Evidence from aging.

The present research tested Tulving's (1985) ternary memory theory. Young (ages 19-32) and older (ages 63-80) adults were given procedural, semantic, and episodic memory tasks. Repetition, lag, and codability were manipulated in a picture-naming task, followed by incidental memory tests. Relative to young adults, older adults exhibited lower levels of recall and recognition, but these episodic measures increased similarly as a function of lag and repetition in both age groups. No age-related deficits emerged in either semantic memory (vocabulary, latency slopes, naming errors, and tip-of-the-tongue responses) or procedural memory (repetition priming magnitude and rate of decline). In addition to the age by memory task dissociations, the manipulation of codability produced slower naming latencies and more naming errors (semantic memory), yet promoted better recall and recognition (episodic memory). Finally, a factor analysis of 11 memory measures revealed three distinct factors, providing additional support for a tripartite memory model.

Persistent repetition priming in picture naming and its dissociation from recognition memory.

The current experiments investigated the longevity of repetition priming and dissociations between different memory measures. Picture-naming latencies revealed robust repetition priming in four separate studies: Previously named pictures were named faster than new pictures. The magnitude of this naming facilitation was stable across 1 to 6 weeks. The apparent temporal invulnerability of repetition priming was in marked contrast to the decline in episodic recognition memory across 6 weeks, suggesting a dissociation between implicit and explicit memory. Additional evidence of this dissociation was observed within each session: Naming facilitation for repeated pictures occurred regardless of whether those particular pictures were consciously recognized.

Transfer of processing in repetition priming: some inappropriate findings.

Transfer effects in repetition priming were found with both picture and word naming, but varied with the type of prime list. Unmixed lists of word or picture primes produced equivalent intra-modal and cross-modal repetition priming in both picture-naming (Experiment 1) and word-naming (Experiment 5) tasks. However, mixing word and picture primes resulted in greater intra-modal than cross-modal priming for both picture-naming (Experiment 2) and word-naming (Experiment 6) tasks. This mixed-list difference between intra-modal and cross-modal priming was reduced by blocking prime types at input (Experiment 3). These findings suggest that differences in priming as a function of prime stimulus format should be cautiously interpreted when mixed prime lists are used.

Tracheal stenosis in Larsen's syndrome.

Larsen's syndrome is known to have an association with laryngomalacia and tracheomalacia. We report a case of Larsen's syndrome with respiratory difficulty due to a tracheal stenosis. To our knowledge, this association has not previously been reported.

Mucoepidermoid carcinoma of the larynx in a child.

Laryngeal carcinoma in childhood is rare and most commonly classified as squamous cell carcinoma. Although mucoepidermoid carcinoma of the larynx has been noted in adults, it has not previously been reported in a child. A 13-year-old boy presented to our department with an epiglottic mass which was determined histologically to be mucoepidermoid carcinoma. A total epiglottectomy was performed and one year postoperatively the child is without disease.

Severe tracheobronchomalacia associated with laryngeal cleft.

We report 3 cases of severe tracheobronchomalacia associated with laryngeal cleft. Each of these children had a major cleft, type 3 in Evans' classification. Separately each of these conditions are difficult to treat, in combination these major airway anomalies caused management problems of great complexity. We describe the presentation of these cases, the diagnosis of the lesions and the management paths we followed. We discuss the pathology of the conditions and the diagnostic options which are available for defining the extent of responsibility of each component to the overall clinical picture. We discuss the therapeutic options available and describe our own management regime.

Emergency treatment of tracheal tear during pharyngolaryngectomy.

Longitudinal tracheal tear (of the trachealis muscle), an unusual but acknowledged complication of pharyngolaryngectomy, was encountered during a total pharyngo-oesophagolaryngectomy with gastric replacement. Due to serious ventilatory difficulties a rapid repair was required to obtain an airtight seal to allow continued mechanical ventilation. A reinforced polytetrafluoroethylene (PTFE) vascular graft was used as an intratracheal stent to seal the air leak. This technique proved effective and the tracheal defect had healed by the time the stent was removed 10 days later.

Growth of a frontal sinus osteoma.

The natural growth of a frontal sinus osteoma is documented in a series of radiographs taken over a period of 17 years in a patient attending St. Thomas' Hospital with untreated acromegaly.

Long-term results of laser-assisted uvulopalatoplasty for snoring.

We present the ongoing results of the series of 53 consecutive patients who underwent laser-assisted uvulopalatoplasty (LAUP) for snoring at the Kent and Canterbury Hospital. Twenty-nine patients (55 per cent) were completely satisfied with their surgery 18 to 24 months following LAUP when previously questioned via telephone questionnaire. We have followed up the 29 patients with a previously successful result at between 70 and 79 months following surgery. They underwent an average of 1.6 procedures. Twelve patients (22 per cent) continue to be completely satisfied at this late stage, and a further 12 (22 per cent) have some ongoing improvement in their snoring. Only three patients have indicated that a previously successful result has failed since the previous survey. The failure rate of LAUP in the treatment of snoring is seen predominantly in the first two years following surgery, but some long-term subjective recurrence of snoring does occur.