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M Dennis

Publications and source records attributed to M Dennis.

At least 37 records · Page 2Linked to original sources
PubMed2001

Knowledge-based inferencing after childhood head injury.

Inferencing was studied with a story comprehension task that required inferences to be made from a controlled knowledge base. Despite similar rates of knowledge base acquisition, knowledge base retention, and speeded access to the knowledge base across groups, the 18 children with severe head injury had lower rates of inferencing than the 15 children with mild head injury or the 18 age-matched controls. Results suggest that cognitive functions such as working memory and metacognitive skill that are disrupted by severe head injury may also play a role in some of the text- and discourse-level deficits commonly reported in these children, notably those involving inferencing.

Adolescent↗
PubMed2001

Poor reading comprehension despite fast word decoding in children with hydrocephalus.

Children with hydrocephalus decode words better than they understand what they read. We tested whether children with hydrocephalus (from myelomeningocele or aqueduct stenosis) (1) decode words slowly, (2) use decoding processes similar to those of neurologically intact peers, and (3) comprehend poorly to the extent that they are slow decoders. We compared speed of word decoding in 33 children with hydrocephalus and 33 controls matched on a pairwise basis for age, grade, and word decoding accuracy. The children with hydrocephalus were as fast as controls in reading words, but, unlike controls, they did not demonstrate an effect of spelling-sound regularity. Further, decoding speed did not contribute to reading comprehension beyond word decoding accuracy. The reading comprehension deficits of good decoders with hydrocephalus are not related to early-stage processing deficits in word recognition speed. Likely origins of comprehension failure in this group are discussed.

Adolescent↗
PubMed2001

Understanding of literal truth, ironic criticism, and deceptive praise following childhood head injury.

Children with closed head injury (CHI) have semantic-pragmatic language problems that include difficulty in understanding and producing both literal and nonliteral statements. For example, they are relatively insensitive to some of the social messages in nonstandard communication as well as to words that code distinctions among mental states. This suggests that they may have difficulty with comprehension tasks involving first- and second-order intentionality, such as those involved in understanding irony and deception. We studied how 6- to 15-year-old children, typically developing or with CHI, interpret scenarios involving literal truth, ironic criticism, and deceptive praise. Children with severe CHI had overall poorer mastery of the task. Even mild CHI impaired the ability to understand the intentionality underlying deceptive praise. CHI, especially biologically significant CHI, appears to place children at risk for failure to understand language as externalized thought.

Child↗
PubMed2001

Attentional-inhibitory control and social-behavioral regulation after childhood closed head injury: do biological, developmental, and recovery variables predict outcome?

Attentional-inhibitory control and social-behavioral regulation are two outcome domains commonly impaired after childhood closed head injury (CHI). We compared neuropsychological tests of attentional-inhibitory control (vigilance, selective attention, response modulation) and social discourse and intentionality (inferencing, figurative language, and speech acts) with parent ratings of attention and behavioral regulation in relation to four injury-related variables: age at CHI, time since CHI, CHI injury severity, and frontal lobe injury moderated by CHI severity. Participants were 105 school-aged children in the chronic stage of CHI, divided into mild, moderate, and severe injury severity groups, and further subdivided according to frontal lobe injury. Outcome indices were imperfectly correlated in the group as a whole, although several relations between neurocognitive tests and parent ratings were observed within CHI subgroups. Different domains of cognitive function had different predictors. For attentional-inhibitory control, age at injury and time since injury were most predictive of outcome; for social discourse, predictors were injury severity and frontal lobe injury moderated by injury severity. Variability in cognitive outcome after childhood CHI is not random, but appears related to age, time, and biological features of the injury.

Adolescent↗
PubMed2001

Inferential language in high-function children with autism.

Despite average verbal intelligence, high-function children with autism have social comprehension deficits that are expressed by how they use and understand language. In this paper, we explored the general hypothesis that high-function children with autism make some, but not all, of the pragmatic inferences necessary for successful communication, even when they have the ability to perform noninferential language tasks. We contrasted the ability of 8 high-function children with autism (each with Verbal IQ > 70) and typically developing children to use and understand: pragmatic inferences about given or presupposed knowledge in mental state words; pragmatic inferences about new or implied knowledge in mental state words; bridging inferences essential for coherence; elaborative inferences involved in enriching a communication by means of figurative language; and the intentional inferences involved in speech acts. High-function children with autism could define words and identify multiple meanings for ambiguous words. In understanding words for mental states, they made inferences from mental state verbs to given or presupposed knowledge. However, they failed to infer what mental state verbs implied in context; to make inferences about social scripts; to understand metaphor; and to produce speech acts, all of which are inferences that are the basis of successful social communication because they elaborate meaning or convey intentions.

Asperger Syndrome↗
PubMed2001

Music skills and the expressive interpretation of music in children with Williams-Beuren syndrome: pitch, rhythm, melodic imagery, phrasing, and musical affect.

This paper studied music in 14 children and adolescents with Williams-Beuren syndrome (WBS), a multi-system neurodevelopmental disorder, and 14 age-matched controls. Five aspects of music were tested. There were two tests of core music domains, pitch discrimination and rhythm discrimination. There were two tests of musical expressiveness, melodic imagery and phrasing. There was one test of musical interpretation, the ability to identify the emotional resonance of a musical excerpt. Music scores were analyzed by means of logistic regressions that modeled outcome (higher or lower music scores) as a function of group membership (WBS or Control) and cognitive age. Compared to age peers, children with WBS had similar levels of musical expressiveness, but were less able to discriminate pitch and rhythm, or to attach a semantic interpretation to emotion in music. Music skill did not vary with cognitive age. Musical strength in individuals with WBS involves not so much formal analytic skill in pitch and rhythm discrimination as a strong engagement with music as a means of expression, play, and, perhaps, improvisation.

Adolescent↗
PubMed2001

Comparison of literal, inferential, and intentional text comprehension in children with mild or severe closed head injury.

BACKGROUND: Children with head injury have impairments in pragmatic language at the level of both single words and texts. Text comprehension deficits are likely to be the more consequential for everyday and academic function, yet the relative magnitudes of literal and nonliteral text comprehension deficits have not been measured. DESIGN: We compared the magnitude of the impairment in three forms of text comprehension for children with mild or severe head injury relative with controls: literal language (understanding literal text information), inferential language (making pragmatic inferences, textual coherence inferences, or enriching inferences), and the language of mental states and intentions (eg, producing speech acts, appreciating irony, and understanding deception). MEASURES: Effect sizes were used to measure the magnitude of the difference between children with head injury and age-matched controls. RESULTS: Children with severe closed-head injury were significantly impaired on tasks of literal text understanding, inferencing, and intentionality. Children with mild head injury were impaired on some inferencing and all intentionality tasks, although they had no literal text comprehension deficits. CONCLUSIONS: For both groups, the greatest deficits (ie, the largest effect sizes) were on tasks requiring understanding of the language of mental states and intentions. The data bear on the long-term effects of childhood closed-head injury on text- and discourse-level language and also on the nature and timing of language rehabilitation in children with head injury.

Adolescent↗
PubMed2001

The psychosocial assessment of deliberate self harm: using clinical audit to improve the quality of the service.

OBJECTIVES: To determine whether simple service initiatives resulted in an improvement in the quality of the psychosocial assessment of adults presenting with deliberate self harm (DSH) by accident and emergency (A&E) medical staff. METHOD: The quality of psychosocial assessment of adults presenting to an A&E department after DSH for a 12 month period was examined using an audit instrument developed from the Royal College of Psychiatrists' standards of service provision for the general hospital management of adult DSH. The results were then compared with a similar audit that had been conducted three years previously. A number of service improvements had been implemented after this first audit. RESULTS: A total of 1359 episodes of adult DSH were identified. When compared with the previous audit, the frequency of information recorded in the case notes was significantly improved in all areas of the psychosocial assessment (p < 0.001) apart from mental state. There were significant changes in treatment between the two audits, with a higher proportion in 1997/8 (362, 26.5%) assessed by a mental health specialist in the department than in 1994/5 (154, 16.5%; chi(2) = 33, p < 0.001). The frequency of recorded information for those who were not admitted directly to medical or surgical wards was significantly higher for all factors (p<0.01) apart from conscious level and medical history. CONCLUSIONS: A substantial improvement in the quality of the psychosocial assessment of adults presenting with DSH by A&E medical staff was achieved with the introduction of simple service developments. Encouraging staff to use a comprehensive checklist, proved particularly beneficial.

Adolescent↗
PubMed2001

Parental causes of death in stroke.

There are many reports of familial aggregation in stroke. However, whether familial aggregation is largely due to genetic or environmental factors is not established. Consecutive subjects with stroke were matched with 2 controls per case of the same sex, born in the same year, district, and whose fathers had the same occupation. Presence on parental death certificates of cerebrovascular disease, other vascular disease, bronchial carcinoma, hypertension, diabetes mellitus and other causes of death was recorded. No significant difference in risk was found for cases having mother (odds ratio, OR 1.08, 95% confidence interval, CI, 0.74-1.57), father (OR 0.91, 95% CI 0.58-1.45) or either parent (OR 1.04, 95% CI 0.74-1.46) with cerebrovascular disease. Familial aggregation may reflect socioeconomic and other environmental factors.

Adult↗
PubMed2001

Systematic review of prognostic models in patients with acute stroke.

Prognostic models in stroke may be useful in clinical practice and research. We systematically reviewed the methodology and results of studies that have identified independent predictors of survival, independence in activities of daily living, and getting home in patients with acute stroke. Eligible studies (published in full in English) included at least 100 patients in whom at least 3 predictor variables were assessed within 30 days of stroke onset and who were followed up for at least 30 days. We recorded 25 indicators of the validity and practicality of each model and identified variables that were consistent independent predictors of each outcome. Eighty-three separate prognostic models were found but most had potentially serious deficiencies in internal and statistical validity, many had limited generalisability, and none had been adequately validated. Only 4 studies met 8 simple quality criteria. Over 150 different predictor variables have been analysed but most were assessed in only 1 or 2 models. None of the existing prognostic models have been sufficiently well developed and validated to be useful in either clinical practice or research. Better quality models must be produced to enable, for example, adequate case-mix correction when comparing outcome among different groups of stroke patients.

Humans↗
PubMed2000

Depression after stroke and lesion location: a systematic review.

BACKGROUND: There is conflicting evidence on the hypothesis that the risk of depression after stroke is influenced by the location of the brain lesion. We undertook a systematic review to examine the hypotheses that depression is more commonly associated with left-hemisphere strokes than with right-hemisphere strokes and with lesions of the left anterior brain than with other regions. METHODS: We did a computer-aided search of MEDLINE, BIDS ISI, and PsychLit databases supplemented by hand searches of key journals. We included all reports on the association of depression after stroke with the location of the brain lesion. Studies were systematically and independently examined by two investigators. Fixed-effects and random-effects meta-analyses were done. FINDINGS: 143 reports were identified by the search strategy. 48 were eligible for inclusion. Not all reports included original data. Only two reports of original data supported the hypotheses and seven clearly did not. The pooled (random-effects) relative risk of depression after a left-hemisphere stroke, compared with a right-hemisphere stroke, was 0.95 (95% CI 0.83-1.10). For depression after a left anterior lesion compared with all other brain areas the pooled (random-effects) relative risk was 1-17 (0.87-1.62). Restriction of the analyses to reports from high-quality studies or major depressive disorder did not substantially affect the findings. Nor were they affected by stratification of the time between stroke and the assessment of depression. Multiple publications from the same samples of patients were apparent. INTERPRETATION: This systematic review offered no support for the hypothesis that the risk of depression after stroke is affected by the location of the brain lesion.

Aphasia↗
PubMed2000

Detection of beta 2-adrenergic receptor dimerization in living cells using bioluminescence resonance energy transfer (BRET).

Heptahelical receptors that interact with heterotrimeric G proteins represent the largest family of proteins involved in signal transduction across biological membranes. Although these receptors generally were believed to be monomeric entities, a growing body of evidence suggests that they may form functionally relevant dimers. However, a definitive demonstration of the existence of G protein-coupled receptor (GPCR) dimers at the surface of living cells is still lacking. Here, using bioluminescence resonance energy transfer (BRET), as a protein-protein interaction assay in whole cells, we unambiguously demonstrate that the human beta(2)-adrenergic receptor (beta(2)AR) forms constitutive homodimers when expressed in HEK-293 cells. Receptor stimulation with the hydrophilic agonist isoproterenol led to an increase in the transfer of energy between beta(2)AR molecules genetically fused to the BRET donor (Renilla luciferase) and acceptor (green fluorescent protein), respectively, indicating that the agonist interacts with receptor dimers at the cell surface. Inhibition of receptor internalization did not prevent agonist-promoted BRET, demonstrating that it did not result from clustering of receptors within endosomes. The notion that receptor dimers exist at the cell surface was confirmed further by the observation that BS3, a cell-impermeable cross-linking agent, increased BRET between beta(2)AR molecules. The selectivity of the constitutive interaction was documented by demonstrating that no BRET occurred between the beta(2)AR and two other unrelated GPCR. In contrast, the well characterized agonist-dependent interaction between the beta(2)AR and the regulatory protein beta-arrestin could be monitored by BRET. Taken together, the data demonstrate that GPCR exist as functional dimers in vivo and that BRET-based assays can be used to study both constitutive and hormone-promoted selective protein-protein interactions.

Animals↗
PubMed2000

The role of gammadelta T cells in generating antiviral factors and beta-chemokines in protection against mucosal simian immunodeficiency virus infection.

In view of the role of gammadelta(+) T cells in mucosal protection against infection, the proportion of gamma delta T cells was examined in cells eluted from lymphoid and mucosal tissues of macaques immunized with simian immunodeficiency virus (SIV) gp120 and p27 in alum and challenged with live SIV by the rectal mucosal route. This revealed a significant increase in gammadelta T cells eluted from the rectal mucosa (p < 0.01) and the related iliac lymph nodes (p < 0.0001) in protected as compared with infected macaques. Preferential homing of PKH-26-labeled gammadelta(+) T cells from the primed iliac lymph nodes to the rectal and cervico-vaginal mucosa was demonstrated after targeted iliac lymph node as compared with i. m. immunization. Investigations of the mechanism of protection revealed that gammadelta(+) T cells can generate antiviral factors, RANTES, macrophage inflammatory protein (MIP)-1alpha and MIP-1beta which can prevent SIV infection by binding to the CCR5 coreceptors. Up-regulation of gammadelta(+) T cells was demonstrated by immunization of macaques with heat shock protein (HSP)70 linked to peptides and with granulocyte-macrophage colony-stimulating factor (GM-CSF). This was confirmed by in vitro studies showing that GM-CSF can up-regulate gammadelta(+) T cells from macaques immunized with HSP-linked peptides but not those from naive animals. We suggest that a novel strategy of immunization with HSP70 linked to antigen may generate both cognate immunity to the antigen and innate immunity by virtue of up-regulation of gammadelta(+) T cells. These cells generate antiviral factors and the three beta-chemokines that prevent binding and transmission of SIV or M-tropic HIV by the CCR5 coreceptor.

Animals↗
PubMed2000

Perception and estimation of time in long-term survivors of childhood posterior fossa tumors.

We examined short duration perception (400 ms), long duration estimation (30 and 60 min), and spatiotemporal estimation in long-term survivors of childhood cerebellar tumors with a mean time since diagnosis of 14.2 years. Groups of individuals with tumors treated with surgery only (astrocytoma, N = 20) were compared to those with tumors treated with surgery, focal radiation, and craniospinal radiation (medulloblastoma, N = 20), and to age-matched controls (N = 40). Childhood lesions of the cerebellum produced enduring deficits in short-duration perception, but spared the ability to functionally estimate long durations, regardless of the pathology or treatment of the tumor. Evidence did not support any functional recovery over time of the cerebellar system that underlies short-duration perception. Younger age at treatment was not a protective factor. Although no group differences were present in the functional measures of long-duration estimation, tumor-related prospective memory deficits interfered with the ability to produce long-duration prospective estimates. The utilization of sensory and somatomotor information to refine real-world spatiotemporal estimates was compromised in the medulloblastoma group only.

Adult↗
PubMed2000

Up-regulation of beta-chemokines and down-modulation of CCR5 co-receptors inhibit simian immunodeficiency virus transmission in non-human primates.

A non-cognate mechanism of protection against human immunodeficiency virus-1 (HIV-1) infection involves up-regulation of beta-chemokines, which bind and may down-modulate the CCR5 co-receptors, thereby preventing transmission of M-tropic HIV-1. The objective of this investigation was to evaluate this mechanism in vivo in non-human primates. Rhesus macaques were immunized by a modified targeted lymph nodes (TLN) route with recombinant simian immunodeficiency virus (SIV) glycoprotein 120 (gp120) and p27 in alum, and adsorbed recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF) with either interleukin (IL)-2 or IL-4. Immunization induced significant increases in the concentrations of CD8 cell-derived suppressor factor (CD8-SF), regulated on activation normal T cells expressed and secreted (RANTES), macrophage inflammatory protein (MIP)-1alpha and MIP-1beta, and down-modulation of the proportion of cells expressing CCR5 (r = 0.737, P<0.05). The macaques were then challenged with SIVmac 220 by the rectal mucosal route. The plasma SIVmac RNA showed a significant inverse correlation with the CD8-SF or the concentration of the three beta-chemokines (r = 0.831 and 0.824, P<0.01), but a positive correlation between the proportion of CCR5+ cells and SIVmac RNA (r = 0.613, P = 0.05). These results demonstrate for the first time in vivo that immunization up-regulates beta-chemokines, which may down-modulate CCR5 co-receptors, and both functions are significantly correlated with the viral load. Hence, the non-cognate beta-chemokine-CCR5 mechanism should be considered as complementary to specific immunity in vaccination against HIV.

Animals↗