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Biomedical subjects

Byung Hwa Lee

Publications and source records attributed to Byung Hwa Lee.

13 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.

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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.

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PubMed2004

A lipophilic sol-gel matrix for the development of a carbonate-selective electrode.

Organic-inorganic hybrid sol-gel matrixes were used as hosts for trifluoroacetyl-p-decylbenzene (TFADB), a traditional ionophore for carbonate. The sol-gel precursor was prepared by the reaction of (3-isocyanopropyl)triethoxysilane with ethylene glycol. Hexadecyltrimethoxysilane (HDTMOS) was employed as a co-precursor. An appropriate amount of tridodecylmethylammonium chloride (TDMAC) and 2-nitrophenyloctyl ether (NPOE) were used as membrane components. On mixing with an acidic catalyst, the sol-state precursors slowly gelled, yielding a membrane in which the active components, TFADB and TDMAC, were encapsulated. Infrared, (1)H, and (29)Si MAS NMR spectrometers were employed to monitor the sol-gel process and the degree of polymerization. The performances of the sol-gel membrane-based electrodes were compared to those of TFADB-based poly(vinyl chloride) (PVC) membrane electrodes. Membranes with a molar ratio of TFADB:TDMAC (1:0.14) showed extended lifetime and stable baseline potential. The response slope toward carbonate was approximately 27 mV/decade between 10(-)(5) and 10(-)(3.5) M at 18 degrees C. Interestingly, selectivity toward carbonate over salicylate and other lipophilic anions was improved, clearly deviating from the Hofmeister selectivity pattern. Responses toward small inorganic anions including chloride and sulfate were negligible. The selectivity coefficients measured by the matched potential method in 0.1 M tris-sulfuric acid buffer, pH 8.75, were log = -0.3, log = -4.2, and log = -2.5.

Journal Article↗
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.

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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.

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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.

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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↗
PubMed2002

Effect of background motion on line bisection performance in normal subjects.

Previous studies have demonstrated that optokinetic stimulation (OKS) influences line bisection (LB) performance in normal subjects and patients with hemispatial neglect. Since subjects were required to attend to stationary targets on a moving background, prior experimental designs might have induced an illusion of target motion or induced motion (IM) in a direction opposite the background. The current study tested whether the IM affects LB performance in normal subjects and how the speed of targets also influences LB. Thirty-two right-handed normal volunteers (aged 28.0 +/- 5.3 years) were asked to bisect stationary lines with a background of horizontal OKS. These stimuli were generated by computer displayed on a large screen via a beam projector. The OKS was varied according to direction (leftward or rightward) and speed (9.4 degrees/sec or 56.1 degrees/sec), producing 4 different experimental conditions. Mean bisection errors in all conditions were compared with a control condition with no background OKS. For each condition, subjects rated the degree of IM on a 5 point scale. With fast rate OKS, subjects reported minimal IM and LB errors were in the same direction as background motion, a finding that replicates previous studies. Conversely, the slow OKS rate caused subjects to report IM and resulted in deviation of the bisection mark in a direction opposite the background OKS. While this discrepancy between the slow and fast OKS conditions might be related to motion illusion, we did not find a direct correlation between the degree of IM and bisection errors and thus reasons for these results remain unexplained.

Adult↗
PubMedDate not supplied

Interchanging scores between clinical dementia rating scale and global deterioration scale.

Clinical Dementia Rating (CDR) scale and Global Deterioration Scale (GDS) are commonly used to measure the severity of dementia. However, no specific rules are available to convert the scores of CDR into those of GDS and vice versa. Using a semi-structured interview, two examiners independently rated CDR and GDS in 78 patients with dementia and 34 controls. Regression analysis showed a curvilinear relationship between CDR and GDS. This curve may provide a rule to interchange the scores of GDS and CDR (or Sum of Boxes of CDR).

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