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Biomedical subjects

Duk L Na

Publications and source records attributed to Duk L Na.

At least 19 recordsLinked to original sources
PubMed2005

Micrographia on free writing versus copying tasks in idiopathic Parkinson's disease.

BACKGROUND: Only a few studies have reported on the frequency of micrographia in idiopathic Parkinson's disease (IPD), and the definition of micrographia in these studies was based simply on the visual inspection of the patients' free writing. OBJECTIVES: We investigated the frequency of consistent (CM) and progressive (PM) micrographia by quantifying the patients' copying of a target letter or figure. METHODS: Seventy-five IPD patients and 30 sex/age matched healthy controls were assigned the tasks of free writing and letter/figure copying. CM was defined by the average size of the letter or figure written or copied by the patients below the controls' mean-2SD. PM was defined by the slope of reduction in size as a function of the serial positioning of the letters/figures below the mean-2SD of the controls. RESULTS: In the free writing, of 75 patients, only one met the criteria for the definition of CM and two met the criteria for the definition of PM definition. In contrast, letter/figure copying tasks identified 33 (44%) patients with CM and 19 (25%) with PM. CONCLUSION: Our study suggests that the prior definition of CM or PM by visual inspection in free writing task is less valid, and that the definition of CM and PM, based on the letter/figure copying tasks rather than free writing tests, could be more objective.

Aged↗
PubMed2005

The influence of illusory motion on line bisection performance in normal subjects.

The present study examines whether illusory movement (IM) of a horizontal line, induced by a moving background (MB), influences line-bisection performance in normal subjects. The first experiment attempted to identify the speeds of MB that induce IM. We found that when speed is increased from 1.53 degrees to 13.3 degrees/sec, IM increases, but that with further speed increases, IM decreases. Leftward MB induces rightward IM, and vice versa. In the second experiment, we had subjects bisect lines at MB speeds that had been shown to induce IM in the first experiment. We found that leftward MB induced a rightward bias, and vice versa. We also found that there was a relationship between the magnitude of IM and the degree of bias. In the third experiment, by making the target line larger than the MB, we made the conditions where IM was presumably absent. Unlike the results of bisection performed with IM, subjects showed a bias in the direction of the MB. Overall, these experiments demonstrated that the perception of motion induces subjects to attend in the direction of movement.

Adult↗
PubMed2005

Left hemispatial visual neglect associated with a combined right occipital and splenial lesion: another disconnection syndrome.

Damage to the left occipital lobe and the splenium or forceps major is often associated with pure alexia, thought to be an occipital-temporoparietal disconnection syndrome. A patient with the parallel lesion, a combined right occipital and splenial lesion, showed severe left-sided visual spatial neglect, but no significant neglect in other sensory modalities. This visual neglect might be related to a disconnection between the visual information processed by the left occipital lobe and the right posterior temporal-inferior parietal areas that mediate attention in the left hemispace.

Aged↗
PubMed2005

Corpus callosum atrophy in Wernicke's encephalopathy.

BACKGROUND AND PURPOSE: Neuropathologic changes in Wernicke's encephalopathy (WE) involve variable brain structures. Corpus callosum involvement in WE, however, is largely unknown. The authors investigated the degree and the pattern of corpus callosum changes in WE according to the etiologies. METHODS: Nineteen patients with WE (between 34 and 81 years) and 19 age- and sex-matched control participants were included. The total cross-sectional callosal area and 5 callosal subregions (C1-C5) were measured by tracing outer margins in the midsagittal sections. Subregions were determined by placing radial dividers with 10 rays. The pixel numbers for corpus callosums were calculated, and the values obtained were adjusted for head size variations. RESULTS: The causes of WE were alcoholism (10), intestinal surgery (5), anorexia (3), and hyperemesis gravidarum (1). The mean size of the total corpus callosum was significantly reduced in alcoholic WE (P< .001; 527.8 +/- 70.8 mm2 for alcoholic WE; 664.6 +/- 58.1 mm2 for the corresponding controls), but not in nonalcoholic WE. In subregion analysis, prefrontal callosum (C2) atrophy was the most prominent in alcoholic WE. In contrast, only splenium (C5) was atrophied in nonalcoholic WE. The degree of atrophy did not change throughout the follow-up period (mean 5.3 weeks). CONCLUSION: This study suggests that the extent and location of corpus callosum atrophy differs between alcoholic WE and nonalcoholic WE, implying separate contribution of alcohol neurotoxicity and nutritional deficiency.

Adult↗
PubMed2005

18F-FDG PET findings in frontotemporal dementia: an SPM analysis of 29 patients.

UNLABELLED: Frontotemporal dementia (FTD) is a common cause of presenile dementia. The aim of the current study was 2-fold: (a) to delineate the brain regions with reduction of glucose metabolism, and (b) to investigate the hemispheric asymmetry of glucose metabolism in FTD using (18)F-FDG PET. METHODS: We compared the regional metabolic patterns on (18)F-FDG PET images obtained from 29 patients with FTD and 11 healthy subjects using a voxel-wise analysis (statistical parametric mapping [SPM]). The hemispheric asymmetry of glucose metabolism was computed based on 2 different measures: one (AI(ROI)) by counting the (18)F-FDG activity of each hemisphere on the normalized and spatially smoothed PET images and the other (AI(SPM)) by counting the number of voxels with significant hypometabolism based on SPM results. RESULTS: Significant hypometabolism was identified in extensive prefrontal areas, cingulate gyri, anterior temporal regions, and the left inferior parietal lobule. Hypometabolism was also found in the bilateral insula and uncus, left putamen and globus pallidus, and medial thalamic structures. Frontal hypometabolism was more prominent in the left hemisphere than in the right. Twenty-six (90%) of the 29 patients with FTD had AI(ROI) values indicating significant lateralization of glucose metabolism; 18 patients had hypometabolism more severe on the left than right side, and only 8 patients had the opposite pattern. Results from AI(SPM) showed similar patterns. CONCLUSION: The voxel-wise analysis of (18)F-FDG PET images of patients with FTD revealed hypometabolism in extensive cortical regions, such as frontal and anterior temporal areas, cingulate gyri, uncus, and insula and subcortical areas, including basal ganglia (putamen and globus pallidus) and medial thalamic regions. The hemispheric asymmetry of hypometabolism (more frequently lateralized to the left) was common in patients with FTD, which may be another metabolic feature that helps to differentiate FTD from Alzheimer's disease or other causes of dementia.

Adult↗
PubMed2004

Visual search pattern during the line quadrisection task in normal subjects.

A common test for the assessment of hemispatial neglect is the line bisection test. A recent modification of the task has been reported wherein subjects place a mark at either 25% or 75% of line length ('quadrisection'). In a previous study, we suggested that line quadrisection might entail iteration of two steps involved in standard line bisection: (1) finding the midpoint of the entire line, and then (2) bisecting the half-line segment between the adjudged midpoint and the line end ipsilateral to the target quadrisection point. The present study investigated eye movement patterns during line quadrisection in order to test this hypothesis. Twenty normal volunteers determined the left or right quadrisection point of a horizontal line while their eye movements were recorded using two-dimensional video-oculography. Analysis revealed that, like the results of previous studies on bisection, most normal subjects fixate the central portion of the line segment before reaching the target area during the quadrisection task. Normal subjects' eye movements during quadrisection performance share a number of features with line bisection and provide support for the two-step processing hypothesis.

Adult↗
PubMed2004

Validation of the Korean version of the Syndrom Kurztest (SKT): a short test for the assessment of memory and attention.

The Syndrom Kurztest SKT is a brief neuropsychological test battery that consists of nine subtests and defines two independent factors of memory and attention deficit. The aim of this study was to validate the Korean version of the SKT. The reliability of each subtest among three parallel Forms (A, B and C) of the Korean version was high (r = 0.46-0.95). The SKT had good concurrent validity with the Mini-Mental State Examination (r = -0.83, p < 0.001). Factor analysis confirmed the presence of two primary factors, memory and attention. The overall similarities of the factor structures for the Korean data and those for the data from Germany and the USA provide evidence of the transcultural stability of the SKT.

Aged↗
PubMed2004

Length perception and production of normal subjects in proximal versus distal peripersonal space.

We investigated whether the perception or production of a given line length in normal subjects varies according to where in peripersonal space the line is perceived or produced. We also investigated the influence of the direction of movement used to make the line. In Experiment 1, blindfolded normal subjects were asked to estimate distances while the examiner moved the subject's hand in proximal (medial) or distal (lateral) space, moving centripetally or centrifugally. The subjects showed a spatial effect, perceiving the same length as shorter in proximal space than distal space. This result could be related to either a proximal spatial attentional bias or an anisometric representation of spatial distances. In Experiment 2, we attempted to dissociate these hypotheses by studying blindfolded normal subjects, who were requested to produce horizontal lines of a given length (100 or 200 mm) in proximal versus distal peripersonal space using centripetal or centrifugal movements. Centrifugal movements in proximal space were the longest; centrifugal movements in distal space were the shortest: in between were the proximal centripetal and distal centripetal movements which did not differ from each other. These results suggest that in peripersonal space the perception of length in normal subjects is most consistent with anisometric mental representation where the size of mental representations of length units decreases as a function of the distance from the subject's midsagittal plane. Length production, however, may depend on an interaction of the anisometric mental representation and the premotor/intentional factors.

Adult↗
PubMed2004

Mechanism of the closing-in phenomenon in a figure copying task in Alzheimer's disease patients.

The"closing-in phenomenon"in figure copying tasks refers to a tendency to copy near the target, or to overlap the target to be copied. The mechanisms underlying the closing-in phenomenon have not been fully elucidated. We posit that closing-in may be related to the patients'compensatory strategies to overcome visuospatial dysfunction or visuospatial working memory deficit. Thus, it is expected that as the complexity of the target figure or the distance from the target to the copying space is increased, the magnitude of closing-in will be increased. Thirteen patients with Alzheimer's disease (AD) who demonstrated closing-in on a screening test and 15 healthy controls participated in this study. Each subject copied figures in conditions that varied in terms of figure complexity and distance from the target to the copying space. Neither figure complexity nor distance between the target and copying space affected the degree of closing-in in normal subjects. In contrast, in AD patients, the magnitude of closing-in increased as a function of figure complexity; however closing-in was unchanged by varying the distance from the target to the copying space. Our results suggest that copying near the target figure might be the patients'strategy to compensate for their visuospatial dysfunction or visuospatial working memory deficits.

Aged↗
PubMed2004

Normative data on the Korean version of the Western Aphasia Battery.

The study aimed to describe the properties of the Korean version of the Western Aphasia Battery (hereinafter K-WAB) and to present the normative data of normal individuals and patients. The K-WAB contains the same test contents and structure as the original WAB and the general test administration method was maintained. We administered the K-WAB to 224 normal adults in seven age groups (1524, 2534, 3544, 4554, 5564, 6574, and 75 years or older), in five educational levels (0, 16, 79, 1012, and 13 years or more) and by gender. The age and educational levels were influential to the K-WAB performance. Accordingly, we formed six subgroups of the normal: two age groups (1574, and 75 years or older groups) by three educational groups (0, 16, and 7 years or more). Two hundred thirty-eight patients were also evaluated using the K-WAB. The highest aphasia quotient (AQ), language quotient (LQ), and cortical quotient (CQ) were achieved by 1574 age group with 7 or more years of education (M=97.11,M=95.51,M=95.57, respectively). Based on the receiver operating curve (ROC) analyses on AQ, LQ and CQ values, cut-off scores to optimally differentiate between the normal and the aphasic individuals were also provided.

Adolescent↗
PubMed2004

Pseudoneglect in solid-line versus character-line bisection tasks: a test for attention dominance theory.

OBJECTIVE: Normal subjects tend to bisect lines slightly to the left of the true midpoint, a phenomenon termed pseudoneglect. To test whether pseudoneglect relates to the right hemisphere's dominance for spatial attention or to the hemispheric difference in processing global-local stimulus properties, we administered conventional solid-line (SBT) and novel character-line (CBT) bisection tasks to normal subjects of different ages. METHODS: Normal subjects, consisting of 40 young and 40 older individuals, received 3 experimental tasks, a standard SBT and 2 types of CBT. Each subject completed 10 consecutive trials of each task presented in counterbalanced order between subjects. RESULTS: Across age groups, deviations on CBT were further to the right than those of SBT, and the leftward bias (pseudoneglect) was significant only in SBT. CONCLUSION: These results indicate that the bisection errors in normal subjects depend on the characteristics demanded by the specific task. Thus, our findings argue against the attention dominance theory and support a "task specificity" theory for pseudoneglect.

Adult↗
PubMed2004

Caregiver-Administered Neuropsychiatric Inventory (CGA-NPI).

The Neuropsychiatric Inventory (NPI) is used to assess neuropsychiatric symptoms in dementia patients. To reduce clinicians' time taken to administer the NPI, the authors studied a caregiver-administered NPI (CGA-NPI), in which caregivers completed the written form of the NPI worksheet. After a brief presupervision session, the caregivers of 61 dementia patients completed the CGA-NPI by reading through the worksheet. This was followed by a postsupervision session to check if the caregivers had completed the form appropriately. The correlation between the prevalence rates of each neuropsychiatric symptom obtained by the CGA-NPI and those obtained by the NPI was fair to good (kappa = 0.57-0.90) in all domains. All frequency, severity, and caregivers' distress scores of the CGA-NPI correlated significantly with those of the NPI (r> 0.6, P<.001). Total CGA-NPI scores also correlated highly with total NPI scores (r= 0.86, P<.001). These results suggest that the CGA-NPI can substitute for the NPI, saving administration time.

Aged↗
PubMed2004

Serial positron emission tomography findings in a patient with hydrocephalic dementia and Alzheimer's disease.

Comorbidity of normal pressure hydrocephalus (NPH) and Alzheimer's disease (AD) is not uncommon. However, few studies have reported the clinical courses of these patients in depth. A 73-year-old woman was confirmed to have AD by a biopsy performed during a shunt operation for NPH after a head trauma. She was followed for 4 years using serial neuropsychological tests and positron emission tomography (PET). Her clinical symptoms remained improved for 2.5 years and then declined. The 1-year minus the presurgical PET scan highlighted the bilateral frontal area, basal ganglia, and thalamus, which may reflect brain regions associated with the improvement of hydrocephalic dementia. On the other hand, the 1-year minus the 4-year scan highlighted the bilateral temporoparietal area and the posterior cingulate gyrus, which may reflect brain regions associated with the aggravation of AD. This subtraction method may be useful for monitoring the clinical course in patients with NPH and AD.

Aged↗
PubMed2003

Validation of the Korean version of the Bayer activities of daily living scale.

The Bayer-activities of daily living (B-ADL) is a brief and internationally applicable ADL instrument which has been validated in three European countries. The B-ADL has been developed to provide a tool for the assessment of functional deficits in performance of every day tasks as they are observed in mild to moderate stages of dementia. The B-ADL has been constructed for use in clinical trials as well as in clinical practice. From an international perspective the major application is the evaluation of treatment effects in clinical studies and the current study was to validate the Korean version of the B-ADL. The B-ADL was administered to a total of 129 subjects with varying degrees of cognitive decline. A substantial cross-sectional correlation between B-ADL and MMSE scores was found. The internal consistency of B-ADL was above 0.98. A factor analysis revealed that a one factor solution accounted for most of the total variance. The B-ADL global score significantly increased as the severity of dementia, assessed by global deterioration scale increased from stage 1 to 5. Test-retest reliabilities of B-ADL global score and each item were very high. All of these results were very similar to those from three European countries except for the proportion of 'non-applicability' in some ADL items. These findings provide evidence that the Korean version of B-ADL can be useful not only for clinical purposes but also for international multicentre studies.

Activities of Daily Living↗
PubMed2003

Hormone replacement therapy in postmenopausal women with Alzheimer's disease: a randomized, prospective study.

OBJECTIVE: To compare the therapeutic efficacy of hormone replacement therapy (HRT) and tacrine in Alzheimer's disease. DESIGN: Six-month, randomized, open-label study. SETTING: University hospital. PATIENT(S): Fifty-five women with mild to moderate Alzheimer's disease were randomly assigned to tacrine (n = 26) or HRT (n = 29). INTERVENTION(S): In the tacrine group, an initial dose of 40 mg/day was increased up to 160 mg/day. In the HRT group, conjugated equine estrogen was given to patients without uteri (n = 3) or together with micronized progesterone to patients with uteri (n = 26). MAIN OUTCOME MEASURE(S): Mini-Mental State Examination (MMSE), Hopkins Verbal Learning Test, Boston Naming Test, Controlled Oral Word Association Test, Geriatric Depression Scale, Hamilton Depression Scale (HDS), and Instrumental Activities of Daily Living (IADL). RESULT(S): Thirty-three patients who completed the outcome measures (tacrine, 17; HRT, 16) were included in an intent-to-treat analysis. The results did not differ between groups except for IADL, which rated more highly after HRT. Apolipoprotein E genotype effects were assessed. MMSE and HDS scores were improved after tacrine treatment in epsilon 4-negative patients. CONCLUSION(S): Overall efficacy of estrogen plus progesterone combination was similar to tacrine for cognition and mood, but greater for ADL. In epsilon 4-negative patients, tacrine is preferable for cognition and mood.

Alzheimer Disease↗
PubMed2003

Caloric stimulation in neglect: evaluation of response as a function of neglect type.

Contralesional neglect may be induced by either unawareness of contralesional stimuli (attentional neglect, AN) or failure to act in contralesional space (intentional neglect, IN). We examined whether contralesional cold caloric stimulation differentially affects AN versus IN. Patients with left-sided neglect (n = 16) from right-hemisphere lesions performed target cancellation and line bisection tasks. Using a video-based apparatus that reverses the right and left side of stimuli, patients with abnormal cancellation performance were divided into those with AN and those with IN. The 5 subjects with normal cancellation performance but rightward bisection bias were also separated into 2 neglect groups. Subjects performed cancellation or bisection tasks before and immediately after irrigation of the left auditory canal with ice water. Caloric stimulation induced brisk rightward nystagmus in all subjects. Subjects with AN cancelled more left-sided targets after stimulation than those with IN (p = .02). Whereas caloric stimulation significantly shifted bisection error leftward for both IN and AN groups (p < .0001), AN patients exhibited a greater magnitude of shift than the IN patients. While the basis for differential performance remains undefined, the data indicate that caloric stimulation influences AN more than IN.

Aged↗