Biomedical subjects

J A Cordes

Publications and source records attributed to J A Cordes.

3 recordsLinked to original sources

PubMed2000

Mechanical and fracture behavior of a fiber-reinforced bioabsorbable material for orthopaedic applications.

Tensile and fracture tests were conducted on thin panels of a fiber-reinforced bioabsorbable material. The composites were made of polycarbonate matrix and calcium phosphate fibers. Both matrix and fibers were bioabsorbable orthopaedic biomaterials. The fibers were short and randomly distributed. The properties were compared for composites with and without a coating of methane on the fibers. Composites with the methane coating had a higher elastic modulus, a higher proportional limit, but a lower load at failure on pre-cracked panels. Electron microscopy showed that the coating resulted in a better bond between the matrix and the fiber.

Journal Article↗

PubMed1998

CLOX: an executive clock drawing task.

OBJECTIVE: To describe a clock drawing task (CLOX) designed to elicit executive impairment and discriminate it from non-executive constructional failure. SUBJECTS: 90 elderly subjects were studied (45 elderly and well persons from the independent living apartments of a continuing care retirement community and 45 patients with probable Alzheimer's disease). The clock drawing performance of elderly patients was compared with that of 62 young adult controls. METHODS: Subjects received the CLOX, an executive test (EXIT25), and the mini mental state examination (MMSE). The CLOX is divided into an unprompted task that is sensitive to executive control (CLOX1) and a copied version that is not (CLOX2). Between rater reliability (27 subjects) was high for both subtests. RESULTS: In elderly subjects, CLOX subscores correlated strongly with cognitive severity (CLOX1: r=-0.83 v the EXIT25; CLOX2: r=0.85 v the MMSE). EXIT25 and MMSE scores predicted CLOX1 scores independently of age or education (F(4,82)=50.7, p<0.001; R2=0.71). The EXIT25 accounted for 68% of CLOX1 variance. Only the MMSE significantly contributed to CLOX2 scores (F(4,72)= 57.2, p<0.001; R2=0.74). CLOX subscales discriminated between patients with Alzheimer's disease and elderly controls (83.1% of cases correctly classified; Wilkes' lambda=0.48, p<0.001), and between Alzheimer's disease subgroups with and without constructional impairment (91.9% of cases correctly classified; Wilkes' lambda=0.31, p<0.001). CONCLUSIONS: The CLOX is an internally consistent measure that is easy to administer and displays good inter-rater reliability. It is strongly associated with cognitive test scores. The pattern of CLOX failures may discriminate clinical dementia subgroups.

Adult↗

PubMedDate not supplied

Frontal MRI findings associated with impairment on the Executive Interview (EXIT25).

We examined the association between the Executive Interview (EXIT25), a bedside measure of executive control, and regional magnetic resonance imaging (MRI) pathology among 52 consecutive geriatric patients presenting to a university dementia assessment clinic. Left frontal (p < .002), left medial (p < .03), right frontal (p < .02), and right medial (p < .02) cortical lesions significantly worsened EXIT25 scores, even after adjusting for age, global cognitive impairment (on the Mini-Mental State Examination), and the severity of cortical dementia on the Qualitative Evaluation of Dementia [QED]. The EXIT25's associations with right hemisphere lesions did not persist after adjusting for left frontal lesions. Left posterior lesions did not significantly affect the EXIT25. Similarly, left frontal circuit pathology worsened EXIT25 scores (p < .05). Pathology in left anterior subcortical structures showed a trend (p = .052). EXIT25 scores were not affected by right subcortical pathology, nor by pathology in either hippocampus. We conclude that the EXIT25 is specifically affected by frontal system MRI lesions, particularly on the left. This conclusion is consistent with earlier functional neuroimaging studies associating EXIT25 performance with left mesiofrontal perfusion.

Aged↗