Inhibitory deficits in children with attention-deficit/hyperactivity disorder: Intentional versus automatic mechanisms of attention

Application of theoretically based tasks to the study of the development of selective attention has led to intriguing new findings concerning the role of inhibitory mechanisms. This study examined inhibitory mechanisms using a countermanding task and an inhibition of return task to compare deficits in intentionally, versus reflexively, controlled inhibition of attention in children with attention deficit hyperactivity disorder. Fifty children with attention-deficit/hyperactivity disorder (ADHD) were classified into one of three subtypes: predominantly inattentive (ADHD/PI), combined (ADHD/C), and those children with ADHD/C who also met criteria for comorbid oppositional defiant disorder (ADHD/C + ODD). The groups were compared to a comparison group of children (n = 21). The countermanding task showed that the ADHD groups required more time to inhibit responses and this impairment did not differ among subtypes. With respect to reflexively controlled inhibition, compared with controls ADHD/C and ADHD/C + ODD groups showed impaired reflexive inhibition, whereas the ADHD/PI group was considerably less impaired. The findings highlight a dissociation between the two forms of inhibitory deficits among children with the inattentive subtype, and raise the possibility that the efficient operation of reflexive inhibitory mechanisms might be necessary for the development of effective intentional control of inhibition

Issues in the Diagnosis of Attention Deficit Disorder: A Cautionary Note on the Gordon Diagnostic System

In a recent paper Gordon (1986) has compared the strengths and weaknesses of traditional microcomputer-based assessment of attention deficit disorder (ADD) with those offered by the Gordon Diagnostic System (GDS; Gordon & McClure 1983; 1984). Not surprisingly, although careful not to overstate the case, he finds GDS to be an improvement over the use of standard microcomputers. Nevertheless, several of his criticisms of microcomputers seem forced, and he tends to downplay some of the more serious concerns associated with the GDS. Given that the GDS is receiving widespread attention, with nationwide marketing procedures underway, it seems fitting to examine its strengths and weaknesses independently as compared to more traditional methods of assessment of attention deficit disorder. To facilitate this goal the history of the GDS will be reviewed since in its relatively brief life several important events have already occurred

The Effects of Stimulant Medication on the Online Story Narrations of Children with ADHD

The current study investigated the inclusion of goal-based story events in the online story narrations of children with ADHD, as compared with their peers, and explored the effect of stimulant medication on the narrations in children with ADHD. Children completed a narration task on two separate occasions. Children with ADHD (n = 17) completed one narration on medication and the other one on placebo. Results indicated that narrations of comparison children (n= 25) were significantly more likely than narrations of children with ADHD to include the story’s positive outcome, completion of the story’s overall goal, and specific attempts linked to the goal. Children with ADHD included a larger total number of clauses in their narrations when on stimulant medication than when on placebo, but medication showed no significant effects for any other variables. Results indicate that stimulant medication may not be effective at reducing goal-based story comprehension deficits in children with ADHD

The Effects of Stimulant Medication on Free Recall of Story Events among Children with ADHD

This study investigated group differences in the recalls of stories by children with attention-deficit/hyperactivity disorder (ADHD) and comparison peers. Further, the study examined whether stimulant medication improved the story recall of children with ADHD relative to a placebo condition. Children were asked to recall both televised and audio taped stories. Free recall protocols were assessed for what information was recalled as a function of story structure features (i.e. status on or off the causal chain and event importance) and were rated for overall coherence. Relative to comparison peers, children with ADHD showed less influence of story structure features on recall, and produced less coherent recall of the audio taped stories. Medication had only limited effects on the story recall of children with ADHD. Specifically, medication did not increase these children’s sensitivity to events central to the stories and had no effect on the coherence of children’s recalls. The implications of the results for guiding future academic interventions are discussed

Online Story Comprehension among Children with ADHD: Which Core Deficits are Involved?

Children with ADHD have difficulty understanding causal connections and goal plans within stories. This study examined mediators of group differences in story narrations between children ages 7-9 with and without ADHD, including as potential mediators both the core deficits of ADHD (i.e., inattention, disinhibition, planning/working memory) as well measures of phonological processing and verbal skills. Forty-nine children with ADHD and 67 non-referred children narrated a wordless book and completed tasks assessing the core deficits of ADHD, phonological processing, and verbal skills. Results revealed that, although no shorter than those of non-referred children, the narratives of children with ADHD contained fewer elements relating to the story’s causal structure and goal plan. Deficits in sustained attention accounted for the most variance in these differences. Results have implications for understanding and ameliorating the academic problems experienced by children with ADHD

Response Style Differences in the Inattentive and Combined Subtypes of Attention-Deficit/Hyperactivity Disorder

This study examined potential differences between the inattentive and combined ADHD subtypes using laboratory tasks assessing behavioral inhibitory processes. Seventy-five children completed two tasks of behavioral inhibition believed to isolate different processes: the cued reaction time task (CRT), a basic inhibition task, and the go/no-go task (GNG), a complex inhibition task that incorporates motivational contingencies. Three groups of participants were identified, including ADHD/Inattentive (n = 17), ADHD/Combined (n = 37), and comparison (n = 21). Results indicated that rather than showing behavioral inhibition deficits, the ADHD/I children appeared overly inhibited, as evidenced by slower reaction times across the two tasks and significantly higher errors of omission in the GNG task. Additionally, the ADHD/I children did not demonstrate cue dependency effects on the CRT task, suggesting that they were failing to incorporate relevant information before making a response. The sluggish and inhibited performance of the ADHD/I group challenges the idea that it is a subtype of ADHD

Ensaio regional de variedades de milho na Região Sul - safra 2008/09.

A rede regional de ensaios de variedades de Milho tem por objetivo avaliar o comportamento de variedades comerciais de milho na região sul do Brasil. O resultado dos ensaios é publicado anualmente no Livro das Indicações Técnicas para o Cultivo de Milho e de Sorgo no RS. Esses resultados também servem para determinação do Valor de Cultivo e Uso (VCU), com vistas à extensão da indicação de uso de cultivares comerciais para o RS

P. falciparum and P. vivax Epitope-Focused VLPs Elicit Sterile Immunity to Blood Stage Infections

In order to design P. falciparum preerythrocytic vaccine candidates, a library of circumsporozoite (CS) T and B cell epitopes displayed on the woodchuck hepatitis virus core antigen (WHcAg) VLP platform was produced. To test the protective efficacy of the WHcAg-CS VLPs, hybrid CS P. berghei/P. falciparum (Pb/Pf) sporozoites were used to challenge immunized mice. VLPs carrying 1 or 2 different CS repeat B cell epitopes and 3 VLPs carrying different CS non-repeat B cell epitopes elicited high levels of anti-insert antibodies (Abs). Whereas, VLPs carrying CS repeat B cell epitopes conferred 98% protection of the liver against a 10,000 Pb/Pf sporozoite challenge, VLPs carrying the CS non-repeat B cell eptiopes were minimally-to-non-protective. One-to-three CS-specific CD4/CD8 T cell sites were also fused to VLPs, which primed CS-specific as well as WHcAg-specific T cells. However, a VLP carrying only the 3 T cell domains failed to protect against a sporozoite challenge, indicating a requirement for anti-CS repeat Abs. A VLP carrying 2 CS repeat B cell epitopes and 3 CS T cell sites in alum adjuvant elicited high titer anti-CS Abs (endpoint dilution titer \u3e1x106) and provided 80–100% protection against blood stage malaria. Using a similar strategy, VLPs were constructed carrying P. vivax CS repeat B cell epitopes (WHc-Pv-78), which elicited high levels of anti-CS Abs and conferred 99% protection of the liver against a 10,000 Pb/Pv sporozoite challenge and elicited sterile immunity to blood stage infection. These results indicate that immunization with epitope-focused VLPs carrying selected B and T cell epitopes from the P.falciparum and P. vivax CS proteins can elicit sterile immunity against blood stage malaria. Hybrid WHcAg-CS VLPs could provide the basis for a bivalent P. falciparum/P. vivax malaria vaccine

A novel malaria vaccine candidate antigen expressed in Tetrahymena thermophila

Development of effective malaria vaccines is hampered by the problem of producing correctly folded Plasmodium proteins for use as vaccine components. We have investigated the use of a novel ciliate expression system, Tetrahymena thermophila, as a P. falciparum vaccine antigen platform. A synthetic vaccine antigen composed of N-terminal and C-terminal regions of merozoite surface protein-1 (MSP-1) was expressed in Tetrahymena thermophila. The recombinant antigen was secreted into the culture medium and purified by monoclonal antibody (mAb) affinity chromatography. The vaccine was immunogenic in MF1 mice, eliciting high antibody titers against both N- and C-terminal components. Sera from immunized animals reacted strongly with P. falciparum parasites from three antigenically different strains by immunofluorescence assays, confirming that the antibodies produced are able to recognize parasite antigens in their native form. Epitope mapping of serum reactivity with a peptide library derived from all three MSP-1 Block 2 serotypes confirmed that the MSP-1 Block 2 hybrid component of the vaccine had effectively targeted all three serotypes of this polymorphic region of MSP-1. This study has successfully demonstrated the use of Tetrahymena thermophila as a recombinant protein expression platform for the production of malaria vaccine antigens

Which executive functioning deficits are associated with AD/HD, ODD/CD and comorbid AD/HD+ODD/CD?

Item does not contain fulltextThis study investigated (1) whether attention deficit/hyperactivity disorder (AD/HD) is associated with executive functioning (EF) deficits while controlling for oppositional defiant disorder/conduct disorder (ODD/CD), (2) whether ODD/CD is associated with EF deficits while controlling for AD/HD, and (3)~whether a combination of AD/HD and ODD/CD is associated with EF deficits (and the possibility that there is no association between EF deficits and AD/HD or ODD/CD in isolation). Subjects were 99~children ages 6–12 years. Three putative domains of EF were investigated using well-validated tests: verbal fluency, working memory, and planning. Independent of ODD/CD, AD/HD was associated with deficits in planning and working memory, but not in verbal fluency. Only teacher rated AD/HD, but not parent rated AD/HD, significantly contributed to the prediction of EF task performance. No EF deficits were associated with ODD/CD. The presence of comorbid AD/HD accounts for the EF deficits in children with comorbid AD/HD+ODD/CD. These results suggest that EF deficits are unique to AD/HD and support the model proposed by R. A. Barkley (1997).17 p