Biomedical subjects

Anh Duong

Publications and source records attributed to Anh Duong.

6 recordsLinked to original sources

PubMed2006

The nature of lexico-semantic processing deficits in mild cognitive impairment.

Lexico-semantic impairments in Alzheimer disease (AD) have been attributed to abnormalities in both intentional and automatic access to semantic memory. However, the order in which these impairments appear during the course of the disease is unclear. We sought to answer this question by documenting lexico-semantic impairments in 61 subjects with mild cognitive impairment (MCI), a pre-AD stage, and by comparing them to those of 39 AD and 60 normal elderly (NE) subjects. All subjects were tested with intentional access tasks (picture naming and semantic probes), automatic access tasks (lexical decision and priming), and executive function tasks (Stroop and Stroop-Picture naming). Results indicated that the MCI group was only impaired on tasks of intentional access relative to the AD group who was impaired on both types of tasks. Because most MCI subjects eventually develop AD, these results suggest that intentional access to semantic memory is impaired before automatic access. Further, impairments on the Stroop-Picture naming task but not on the Stroop task, suggest that lexico-semantic impairments in the MCI group may be related to inhibition deficits during semantic search. Findings are discussed in light of executive dysfunctions within the framework of semantic memory theories.

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PubMed2005

The heterogeneity of picture-supported narratives in Alzheimer's disease.

This study describes discourse patterns produced by 46 Alzheimer disease (AD) patients and 53 normal elderly subjects in two picture-supported narratives. Nine measures derived from a cognitive model of discourse processing were obtained and submitted to cluster analysis. Results indicate that discourse patterns elicited from both stimuli were heterogeneous. Further, they fail to clearly differentiate between normal aging and AD in half of the AD patients. Discourse patterns are examined in light of various sources of heterogeneity including severity of cognitive impairment, subject characteristics, and task demands. The usefulness of discourse as a diagnostic and therapeutic tool is discussed.

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PubMed2005

Three years experience with monopolar and bipolar radiofrequency ablation surgery in patients with permanent atrial fibrillation.

OBJECTIVE: In our population permanent atrial fibrillation (pAF) is a frequent concomitant problem in patients undergoing open heart surgery. A 3-year experience with a treatment strategy using mono- and bipolar radiofrequency (RF) ablation procedures in a heterogeneous group of patients is reported. METHODS: In a prospective analysis the incidence of pAF among all patients undergoing open heart surgery in our department between February 2001 and July 2004 was evaluated. In a second step a selective group of 106 patients with pAF (primary mitral: n=63; aortic: n=24; CABG: n=16; aortic+mitral: n=3) underwent either monopolar (n=86) or bipolar (n=20) RF ablation procedures creating two encircling isolation lesions around the left and the right pulmonary veins (PVs) and a connection line between both. In addition amiodarone was given for 3 months after surgery. Regular follow-ups were performed 3, 6, 9, 12, 18, 24 and 36 months after surgery. RESULTS: The incidence of pAF in the total group of 4.110 patients was 3.6%. While the rate was low in cases without severe heart valve disease (1.1%), a significantly higher presence of pAF in patients scheduled for heart valve surgery (10.3%) was observed (P<0.0001). The incidence was 30-39% in patients with degenerative and rheumatic mitral valve (MV) disease, and further particularly high in the older aged compared to younger patients (4.2-8.3% at 70-99 years; P<0.001). Hospital mortality after combined open heart and RF ablation surgery was 1.9%. Whereas patients with small left atrial size (LA-diameters <56 mm; n=59) had SR in almost 90% at follow-up, LA enlargement (LA-diameter > or =56 mm; n=47) was associated with a significant risk of persisting pAF after surgery (P=0.033, 0.002 and 0.006 at 3, 6 and 9 months follow-up). CONCLUSION: The use of RF ablation procedures in combination with amiodarone therapy represents a safe and efficient option to cure pAF during open heart surgery in a selective group of patients. The preoperative LA size was of significant importance for the outcome in this investigation.

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PubMed2005

Role of interferon-gamma in a mouse model of allergic conjunctivitis.

PURPOSE: To characterize the effect of repeated topical exposure to allergen in a mouse model of allergic conjunctivitis and to determine the role of interferon-gamma (IFN-gamma) in the pathogenesis of allergic conjunctivitis. METHODS: Wild-type BALB/c mice and IFN-gamma knockout (KO) BALB/c mice were sensitized in the footpad with short ragweed (SRW) allergen and challenged topically for seven consecutive days with SRW allergen. The number of splenic CD4(+) Th2 cells was determined by flow cytometry, and the cytokine profile of CD4(+) T cells from SRW-sensitized mice was evaluated by ELISA. The role of IFN-gamma in allergic conjunctivitis was also examined by timed in vivo neutralization with anti-IFN-gamma antibody. Allergic conjunctivitis was evaluated clinically and histopathologically. RESULTS: Repeated topical challenge with SRW allergen induced allergic conjunctivitis that was characterized by lid edema, chemosis, redness, and tearing. Histopathological analysis revealed a marked conjunctival infiltrate that was predominantly neutrophils and eosinophils. IFN-gamma KO mice and normal mice treated with anti-IFN-gamma antibody displayed milder clinical symptoms of allergic conjunctivitis and a 70% reduction in the number of eosinophils that infiltrated the conjunctiva. Spleen cells from SRW-sensitized mice contained a large population of cells that expressed the Th2 surface marker T1/ST2 and produced IL-4, -5, and -10 and IFN-gamma after stimulation with SRW allergen. CONCLUSIONS: Repeated topical application of SRW allergen induces a form of murine allergic conjunctivitis that mimics the human counterpart. IFN-gamma appears to contribute to the pathogenesis of murine allergic conjunctivitis at the effector phase, but not during the initial sensitization stage.

Allergens↗

PubMed2005

[Communication, discourse and dementia].

The construction-integration model (Kintsch, 1988) offers a frame for discourse analysis. This model defines four representation levels: the surface level or linguistic form, the base text or semantic level, the situation model built by combining information from the text and personal world knowledge, and the organization level. This study describes discourse produced by 46 Alzheimer patients and 53 normal elderly subjects in two picture-elicited production tasks: a single picture and a sequence of pictures. Globally, the single picture task is a more difficult situation for Alzheimer patients. The impaired levels in dementia are surface level, situation model and organization. Therefore, Kintsch model allows a distinction among discourse productions by normal elderly and mild to moderate Alzheimer patients.

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PubMed2003

Discourse about discourse: what is it and how does it progress in Alzheimer's disease?

Discourse about discourse or a subject's comments about his/her performance during a discourse task can be defined as modalizing discourse (discours modalisateur; [Nespoulous, 1980]; [Nespoulous et al., 1998]). Since it does not convey the expected content of the discourse task (referential discourse), modalizing discourse has often been considered non-informative, and as such, has received little interest. The present study investigated the modalizing aspect of discourse production and its evolution in Alzheimer's disease (AD). Five AD patients produced a picture-induced narrative across five consecutive assessments. Two measures were derived: the modalizing/referential ratio (M/R ratio) and the percentage of repeated ideas. Results revealed that, compared to a group of 27 normal controls matched for age and education, AD patients: (1) obtained higher M/R ratios that tended to diminish as the number of assessments increased, and (2) produced higher percentages of repeated ideas throughout all assessments. These results suggest that modalizing discourse makes up a large proportion of AD patients' discourse and should be included in further studies to accurately describe their discourse behavior. The implications of modalizing discourse on preserved pragmatic abilities and its inclusion in comprehensive management programs of AD patients are discussed.

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