Search PubMed⌕ Search

Biomedical subjects

C K Liu

Publications and source records attributed to C K Liu.

At least 37 records · Page 2Linked to original sources
PubMed1998

Infection of glial cells by the human polyomavirus JC is mediated by an N-linked glycoprotein containing terminal alpha(2-6)-linked sialic acids.

The human JC polyomavirus (JCV) is the etiologic agent of the fatal central nervous system (CNS) demyelinating disease progressive multifocal leukoencephalopathy (PML). PML typically occurs in immunosuppressed patients and is the direct result of JCV infection of oligodendrocytes. The initial event in infection of cells by JCV is attachment of the virus to receptors present on the surface of a susceptible cell. Our laboratory has been studying this critical event in the life cycle of JCV, and we have found that JCV binds to a limited number of cell surface receptors on human glial cells that are not shared by the related polyomavirus simian virus 40 (C. K. Liu, A. P. Hope, and W. J. Atwood, J. Neurovirol. 4:49-58, 1998). To further characterize specific JCV receptors on human glial cells, we tested specific neuraminidases, proteases, and phospholipases for the ability to inhibit JCV binding to and infection of glial cells. Several of the enzymes tested were capable of inhibiting virus binding to cells, but only neuraminidase was capable of inhibiting infection. The ability of neuraminidase to inhibit infection correlated with its ability to remove both alpha(2-3)- and alpha(2-6)-linked sialic acids from glial cells. A recombinant neuraminidase that specifically removes the alpha(2-3) linkage of sialic acid had no effect on virus binding or infection. A competition assay between virus and sialic acid-specific lectins that recognize either the alpha(2-3) or the alpha(2-6) linkage revealed that JCV preferentially interacts with alpha(2-6)-linked sialic acids on glial cells. Treatment of glial cells with tunicamycin, but not with benzyl N-acetyl-alpha-D-galactosaminide, inhibited infection by JCV, indicating that the sialylated JCV receptor is an N-linked glycoprotein. As sialic acid containing glycoproteins play a fundamental role in mediating many virus-cell and cell-cell recognition processes, it will be of interest to determine what role these receptors play in the pathogenesis of PML.

Acetylgalactosamine↗
PubMed1998

Incidence and subtypes of dementia in southern Taiwan: impact of socio-demographic factors.

OBJECTIVE: To determine the incidence rate (IR) and subtypes of dementia in southern Taiwan. METHODS: From a cohort of 2,915 community inhabitants aged 65 years and over, 2,507 and 2,175 subjects participated in the first- and second-year follow-up surveys, respectively. A two-phase study used the Mini-Mental State Examination in phase I and the Consortium to Establish a Registry of Alzheimer's Disease (CERAD) neuropsychological battery and the neurobehavioral examination in phase II. We applied International Classification of Diseases (ICD)-10NA criteria for dementia, National Institute of Neurological and Communication Disorders and Stroke-Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA) guidelines for Alzheimer's disease (AD), and National Institute of Neurological Disorders and Stroke-Association Internationale pour la Recherche et l'Enseignement en Neurosciences (NINDS-AIREN) criteria for vascular dementia (VaD). RESULTS: The annual IR for total dementia was 1.28%, which increased with age from 0.77% for 65- to 74-year-olds to 6.19% for persons aged 85 years or older. AD (25 cases, 41.7%, IR=0.54%) was the most common cause of dementia, followed by VaD (19 cases, 31.7%, IR=0.41%) and mixed dementia (9 cases, 15.0%). After adjusting for sex, increasing age was significantly associated with total dementia and AD (p < 0.01). Illiteracy was associated with a marginally increased risk for total dementia (aRR=1.59, p < 0.1) as was being female for AD (aRR = 1.92, p < 0.1). The 2-year mortality rate was high among the demented (48% in total dementia, 38% in AD, and 60% in VaD). CONCLUSIONS: The age-specific incidence of dementia in Taiwan is approaching that of developed countries and the low prevalence of dementia (especially VaD) may be mainly due to the high mortality. Age was the major risk factor for total dementia and AD. Being female was probably a risk factor for AD, as was illiteracy for total dementia.

Age Distribution↗
PubMed1998

The human polyomavirus, JCV, does not share receptor specificity with SV40 on human glial cells.

The initial event in the life cycle of a virus is its interaction with specific receptors present on the surface of a cell. Understanding these interactions is important to our understanding of viral tropism and tissue specific pathology associated with viral disease. The human polyomavirus, JCV, is the etiological agent of the fatal central nervous system (CNS) demyelinating disease, progressive multifocal leukoencephalopathy (PML). PML is the direct result of JCV infection of oligodendrocytes, the myelin producing cell in the CNS. In vivo, JCV can be detected in oligodendrocytes, astrocytes, lymphoid tissue, and peripheral blood of PML patients. In vitro, JCV infects human glial cells, tonsilar stromal cells, and, to a limited extent, human B lymphocytes. The initial step in infection of cells by JCV is at the level of attachment and entry. A specific cell surface receptor for JCV on human glial cells has not been identified. To begin to understand the nature of JCV receptors on human glial cells, large quantities of a previously characterized hybrid JC virus (Mad-1/SVEdelta) were purified. A direct virus binding assay demonstrated that these highly purified and labeled JCV virions bound to a finite number of cellular receptors on human glial cells. A competitive virus binding assay demonstrated that an excess of unlabeled JCV competed with labeled JCV more efficiently than did an excess of purified SV40. Furthermore, anti-class I antibodies which inhibited infection of glial cells by SV40 had no significant effect on infection by JCV. These results imply that JCV does not share receptor specificity with the related polyomavirus, SV40.

Animals↗
PubMed1998

Cranial computed tomography in ischemic stroke patients with and without dementia--a prospective study.

Stroke patients were assessed by brain CT scan, accompanied by demographic and clinical factors to predict the development of dementia following an ischemic episode. Vascular dementia was defined by NINDS-AIREN criteria. From 50 demented and 50 non-demented stroke patients, we analyzed the location of lesion, counted the numbers of lacunae, and semiquantitatively assessed the size of infarction, severity of overall white matter lesions (WML), and degree of brain atrophy. Compared to the non-demented patients, the demented patients: 1) encountered more stroke episodes (p < 0.001); 2) had more lacunae at bilateral basal ganglion (p < 0.001) or thalamus (p < 0.01); and 3) tended to have lesions in left cortex (p < 0.001), particularly a large infarct at the parietal (p < 0.001) or temporal lobe (p < 0.001). Periventricular changes (p < 0.001), subcortical WML (p < 0.001), overall WML (p < 0.001), and brain atrophy (p < 0.05) were also more severe in the demented group. However, no difference existed in demographic factors between the two groups. We concluded that several factors were important in developing dementia following an ischemic stroke, and the order by logistic regression would be: the severity of overall WML, left parietal infarct, and numbers of thalamic lacunae.

Aged↗
PubMed1998

A study of central and peripheral nerve conduction in patients with primary hypothyroidism: the effects of thyroxine replacement.

Somato-Sensory Evoked Potential (SSEP) and Peripheral Nerve Conduction (PNC) studies were performed in twenty patients with primary hypothyroidism to elucidate the changes of central and peripheral nervous systems in hypothyroid state and the effects of thyroxine replacement. Before thyroxine replacement therapy, eleven patients had significantly delayed SSEP (prolonged latencies of N9, N13, or N20), and only three patients had prolonged central conduction time (between N13 and N20). PNC abnormalities with decreased conduction velocity and diminished amplitudes were found in fourteen patients. After thyroxine treatment, both SSEP and PNC studies demonstrated significant improvement and paralleled the clinical neurological amelioration. The central and peripheral conduction velocities returned to normal limits, while the abnormality in amplitude still persisted. There were also discrepancies between SSEP and PNC studies in both the abnormality pattern and the recovery potential. Our observations may suggest: firstly, both the SSEP and PNC studies may be useful, alternative tools in monitoring the neurological disorders in hypothyroidism; and secondly, the pathogenesis of central and peripheral nervous dysfunction in hypothyroidism may be via different mechanisms.

Adult↗
PubMed1998

[A central nerve conduction study in hypothyroidism: before and after thyroxine replacement].

Employing a Nicolet CA 100 machine, 20 patients of primary hypothyroidism were selected for electrophysiological studies, including somato-sensory evoked potential (SSEP), brainstem auditory evoked potential (BAEP), and visual evoked potential (VEP), to assess the central nerve conduction before and after administration of the thyroid hormone. Before thyroxine replacement therapy, the latencies of N9, N13, and N20 in SSEP showed significant delay, while the central conduction time (CCT) merely had a tendency of prolongation. In BAEP, the peak and interpeak latencies delayed significantly. Additionally, the latency and amplitude of VEP also had significant difference between patients and controls. After thyroxine replacement, the SSEP, BAEP, and VEP studies revealed significant improvement, in correlation with clinical amelioration. In conclusion, the central nerve conduction would be affected in primary hypothyroidism and the improvement was usually the case, reflecting the clinical recovery after appropriate treatment. The electrophysiological study provides an objective method for monitoring the function of central nervous system in hypothyroidism before and after thyroxine treatment.

Adult↗
PubMed1997

A longitudinal study of central and peripheral nerve conduction in hypothyroid rats.

In order to detect the dysfunction of central and peripheral nervous systems among rats with varied duration of hypothyroidism and to elucidate the pattern of recovery after thyroxine replacement, a series of BAEP and PNCS (Peripheral Nerve Conduction Study) were conducted and compared with age-matched controls. BAEP and PNCS were performed in three groups of hypothyroid animals 1, 3 and 5 months after thyroidectomy, respectively. Following initial electrophysiological assessment, thyroxine replacement was administered to each group of hypothyroid rats, and BAEP and PNCS were performed at two month intervals, up to two successive normal studies, or six months after the initiation of therapy, whichever came first. For BAEP, prolonged I-V interpeak latency was the most consistent abnormal finding in all groups of hypothyroid rats, and longer hypothyroid states correlated well with more severe central conduction disorder. Nevertheless, these abnormalities usually returned to normal after thyroxine replacement if the duration of hypothyroidism was less than 5 months. Regarding PNCS, all groups of thyroidectomized rats showed normal conduction before and after thyroxine therapy. The present study indicates that, in rats: (1) the peripheral nervous system seems to be more resistant to hypothyroidism than the central nervous system, or (2) the pathogenesis of central and peripheral nerve dysfunction in hypothyroid rats may occur through different mechanisms.

Age Factors↗
PubMed1997

The psychiatric manifestation of Creutzfeldt-Jakob disease.

Creutzfeldt-Jakob disease (CJD) is considered to be very rare in the population, and the psychiatric manifestation of the disease even rarer with only one report in the past few years in Taiwan. To clarify whether the psychiatric manifestation of CJD is really rare or whether it is neglected in Taiwan, the authors reviewed the discharge notes of patients who had been admitted to a neurological unit in the past 15 years and conducted a chart review of the patients of CJD supported by the clinical courses, EEG finding and brain biopsies. An inquiry was made by telephoning their families to follow up their condition after discharge. Five of the 8 cases with CJD had psychiatric symptoms including changes of mood, thought, behavior and perception during their course of illness. Four cases had been sent to the psychiatric unit and received treatment under several kinds of psychiatric diagnoses. Two patients had been admitted to the psychiatric unit and one had received electroconvulsive treatment. Two of the patients had been suspected to be the victims of neuroleptic malignant syndrome. It is likely that it is psychiatrists who will meet CJD patients first in the early stages of disease. CJD should be kept in mind and EEGs with detailed neurological checkups should be completed, if the cognitive functions of the patients with unusual neurological symptoms deteriorate quickly and their psychiatric symptoms fail to respond to any treatment.

Aged↗
PubMed1996

Prevalence of dementia in an urban area in taiwan.

This two-stage epidemiologic study was to investigate the prevalence and types of dementia among elderly people in the Saa-Min district of Kaohsiung City in Taiwan. In stage one, the Chinese Mini-Mental Status Examination (CMMSE) and Blessed Dementia Rating Scale were employed. In stage two, a comprehensive neurobehavioral examination and neuropsychologic tests were administered by neurologists and neuropsychologists. Dementia was defined by DSM-III-R criteria. The National Institute of Neurological and Communication Disorders and Stroke-Alzheimer's Disease and Related Disorders Association guidelines for Alzheimer's disease (AD) and the National Institute of Neurological Disorder and Stroke-Association international pour la Recherche et l'Enseignement en Neurosciences criteria for vascular dementia (VaD) were applied. A total of 1,016 randomly selected elderly people participated in phase one: 131 people with CMMSE below cutoff values participated in phase two, of whom 45 were confirmed to have a form of dementia. The prevalence of dementia in this sample was 4.4% (3.2% in men and 5.8% in women): 2.0% for those 65 to 74 years old, 8.3% for those 75 to 84 and 24.4% for those > or = 85 years old; 6.0% for those who were illiterate, 3.3% for those who attended grade-school; and 2.8% for those who finished junior-high-school. AD (22 cases, 48.9%) was the most common cause of dementia, followed by VaD (11 cases, 24.4%) and mixed dementia (MIX: 5 cases, 11.1%). Old age and being female were significant high risk factors for AD. Medical history indicated that stroke and hypertension were significant risk factors for VaD. A relatively high prevalence of dementia was observed in this study, probably because we assessed neurobehavior in great detail. Although AD was the leading cause of dementia in the present population sample. VaD and MIX also comprised an important proportion, reflecting the high prevalence of stroke in Taiwan. Older women had high risk for AD, not for VaD; and those with a history of stroke and hypertension had high risk for VaD, not for AD.

Aged↗
PubMed1995

[The changes of central and peripheral nerve conduction and the effect of thyroxine replacement in thyroidectomized rats].

The aim of this study is to make serial BAEPs and PNCS in hypothyroid rats in order to provide objective and quantitative methods of detecting dysfunction of the central and peripheral nervous system in hypothyroid status and elucidating the relationship between the recovery potential and the duration of hypothyroid status. Thyroidectomy was performed in eighteen naive 5-month-old Sprague-Dawley rats in order to induce hypothyroid status, which was confirmed by RIA study 1-2 months after the surgery. Initial BAEP and PNCS were performed in two groups of the hypothyroid animals 1 and 3 months after thyroidectomy. Following the initial examination, thyroxin replacement therapy was given to each hypothyroid group, and then followed by BAEPs and PNCS at two month intervals, up to twice normal studies or six months after the initiation of therapy. In the BAEP study, the prolonged I-V inter-peak latency was the most consistent abnormal finding in all hypothyroid rats. Delayed peak latencies as well as prolonged I-III and III-V inter-peak intervals occurred when the hypothyroid status was longer than one month. We noted that the longer the hypothyroid status, the more severe the central conduction dysfunction. Nonetheless, these abnormalities always returned to normal after the replacement therapy if the hypothyroid state was shorter than 3 months in duration. For the PNCS study, all groups of thyroidectomized rats showed the normal results. We think the peripheral nervous system of rats may be more resistant to damage by hypothyroidism than the central nervous system.

Animals↗
PubMed1994

MR imaging evaluation of bone marrow signal change in post-irradiation patients with nasopharyngeal carcinoma.

BACKGROUND: The normal distribution of red and yellow marrow can be altered by therapeutic irradiation, which causes a well-documented sequence of bone marrow changes. This study measured the T1 signal intensity of the clivus and cervical vertebral bodies of NPC patients who had received a complete course of radiation therapy. METHODS: There were 3 categories of patients: Group I: NPC patients who had radiation myelitis; 14 persons which a total 20 times of MRI. Group II: NPC patients, without radiation myelitis; 6 patients, which a total 6 times of MRI. Group III (control group): patients who received MRI of the cervical spine because of cervical spondylosis or HIVD, were total of 45 patients. In the sagittal section of T1WI, the signal intensity of the bone marrow of clivus and C2 to T1 vertebral bodies was measured. RESULTS: 1). There were homogeneous increases of signal intensity of the bone marrow of clivus and C2 to T1 in Groups I and II. 2). There was no statistical difference between Groups I and II. 3). The increased signal intensity of bone marrow after radiation showed no difference in short and long duration between radiation therapy and MR examinations, indicating that bone marrow signal intensities were increased in NPC patients whether or not they had radiation myelitis. CONCLUSIONS: Signal change in bone marrow may have occurred soon after radiation therapy, and may have persisted for several years. The radiation myelitis always involved the low medulla oblongata to C5 level; however, the bone marrow signal change always extended downward to the T1 level, so bone marrow is more sensitive than the spinal cord and is prone to be affected by irradiation.

Adult↗
PubMed1992

A quantitative MRI study of vascular dementia.

We studied the MRI and clinical factors associated with dementia following stroke by quantifying ventricle-to-brain ratio (VBR), anatomic region of infarction, and cortical, subcortical, and white matter areas of infarction in 24 stroke patients with dementia and 29 nondemented stroke patients. The factors that most strongly correlated with dementia were total white matter lesion (WML) area, left WML, VBR, right WML, age, left cortical infarction area, left parietal infarction area, and total infarction area. Using discriminant analysis, these factors correctly classified 28 of 29 nondemented patients and 18 of 24 demented patients. Both cortical and white matter total infarction area measurements were strongly associated with dementia in stroke patients, suggesting that these factors strongly influenced the development of dementia following stroke. There was a strong association between dementia and left- but not right-hemisphere infarction area. The only demographic factor that strongly associated with dementia was age.

Aged↗
PubMed1992

Types of dementia in Taiwan--a prospective study.

We prospectively investigated 100 consecutive inpatients with suspected dementia to evaluate the relative frequency of various types of dementia in a general hospital of Taiwan. Dementia was confirmed in 86 cases (86%) according to the dementia criteria of the third revised edition of the Diagnostic and Statistical Manual of Mental Disorders and Clinical Dementia Rating Scale (greater than or equal to 1). In contrast to the western developed countries, vascular dementia (VD) (35%) was the leading type of dementia, followed by Alzheimer's disease (AD) (27%), mixed VD and AD (MIX) (14%), and other degenerative diseases (10%). Ten cases (11.6%) of potentially treatable dementia were identified and 8 of 10 had good improvement after appropriate treatment. There were significant age differences among patients with MIX, AD and VD (p less than 0.01). Those with MIX were the oldest (72.12 +/- 9.4) followed by AD (69.70 +/- 8.52) and VD (64.81 +/- 9.12). Males were slightly predominant in this series (male:female = 50:36). A comprehensive clinical investigation including laboratory tests, electroencephalography and CT are necessary in the assessment of demented patients in order to make correct etiological diagnoses which lead to appropriate treatment or management of this terrifying syndrome.

Adult↗
PubMed1991

Watershed infarcts, Tc-99m HMPAO SPECT and CT correlation. Case reports.

We report on the use of Tc-99m hexamethylpropylene amineoxime (HMPAO) in watershed infarcts in five patients who had focal neurologic symptoms. Good correlation between Tc-99m HMPAO and CT was found in two patients. In three patients only Tc-99m HMPAO SPECT in a watershed distribution showed a perfusion abnormality that explained the clinical findings. Tc-99m HMPAO SPECT may be more sensitive than CT in the detection of infarctions in the watershed distribution.

Adult↗
PubMed1989

[The effects of metrizamide myelography on electroencephalographic changes].

Metrizamide, a non-ionic water soluble contrast medium, is used in myelography for detecting spinal cord lesions. Because it is an injection in the subarachnoid space, the effects on the central nervous system following metrizamide myelography should be studied. Electroencephalography can offer a non-invasive and objective method for evaluating the functions of the central nervous system. From September to December 1986, 30 cases which had received cervical or lumbar metrizamide myelography were collected. After myelography, in addition to a history review and neurologic examination, electro-encephalography was carried out within 24 hours. If the EEG record revealed abnormal, a series of EEG follow-ups were conducted until recordings were normal. The incidence of clinical adverse effects following Metrizamide myelography was 53.3% and 66.6% respectively in cervical and lumbar injections. No significant difference was found between the two groups. Secondly, the abnormal rate of the EEG record was 40.0% and 60.0% following cervical and lumbar myelography. The difference was also not significant. Lastly, the relation between clinical adverse effects and an abnormal EEG records was poor in cervical metrizamide myelography but good in lumbar myelography. The conclusions suggested by this research that the clinical adverse effects and the abnormal EEG record after metrizamide myelography are transient and are reversible changes. The mechanism of complications following cervical and lumbar metrizamide are different. Although complications may occur following cervical and lumbar metrizamide myelography, it remains a practical method in detecting spinal cord lesions.

Adult↗
PubMed1988

Thromboembolic complications in coronary angiography associated with the use of nonionic contrast medium.

Thromboembolic complications occurred during diagnostic coronary arteriography in three patients in spite of systemic heparinization. These mishaps were associated with the use of a nonionic contrast medium, which is known not to have a significant protective effect on coagulation pathways. If nonionic contrast media are to be used in angiographic studies of critical organs, meticulous technique is imperative, and adequate systemic heparinization is recommended.

Aged↗