Biomedical subjects

R C Chen

Publications and source records attributed to R C Chen.

At least 37 records · Page 2Linked to original sources

PubMed1997

Churg-Strauss syndrome presented as multiple intracerebral hemorrhage.

Intracerebral hemorrhage is an uncommon sequel of Churg-Strauss syndrome. We describe a 27 y old Taiwanese male patient who was clinicopathologically diagnosed as Churg-Strauss syndrome. The patient experienced a sudden onset of blurring of vision and slowness of motion and speech. Magnetic resonance imaging of the brain revealed lobar hemorrhage on right parieto-occipital and left parietal areas. The cause of cerebral hemorrhage was probably due to poorly controlled high blood pressure and vasculitis. He received pulse therapy of methylprednisolone and cyclophosphamide followed by oral prednisolone. His neurological symptoms responded well to such a regimen. Cerebral hemorrhage is a major cause of morbidity and death in patients with Churg-Strauss syndrome. Uncontrolled high blood pressure may cause cerebral hemorrhage. Careful monitor of blood pressure is critical for the management of Churg-Strauss syndrome patients.

Adult↗

PubMed1997

Environmental risk factors and Parkinson's disease: a case-control study in Taiwan.

To explore environmental risk factors for Parkinson's disease (PD) in Taiwan, we investigated 120 patients with PD and 240 hospital control subjects matched with patients on age (+/-2 years) and sex. Based on a structured open-ended questionnaire, we carried out standardized interviews to obtain history of exposure to environmental factors, including place of residence, source of drinking water, and environmental and occupational exposures to various agricultural chemicals. In the univariate analysis, the history of living in a rural environment, farming, use of herbicides/pesticides, and use of paraquat were associated with an increased PD risk in a dose-response relationship. After adjustment for multiple risk factors through conditional logistic regression, the biological gradient between PD and previous uses of herbicides/pesticides and paraquat remained significant. The PD risk was greater among subjects who had used paraquat and other herbicides/pesticides than those who had used herbicides/pesticides other than paraquat. There were no significant differences in occupational exposures to chemicals, heavy metals, and minerals between PD patients and matched control subjects. The duration of drinking well water and alcohol consumption was not significantly associated with PD. There was an inverse relationship between cigarette smoking and PD. Environmental factors, especially exposures to paraquat and herbicides/pesticides, may play important roles in the development of PD in Taiwan.

Adult↗

PubMed1996

Is ataxic gait the predominant presenting manifestation of Creutzfeldt-Jakob disease? Experience of 14 Chinese cases from Taiwan.

Creutzfeldt-Jakob disease (CJD) is caused by an unusual prion protein. Rare CJD cases have been reported in Chinese individuals. This report describes the clinical manifestations of 14 Chinese individuals with clinically definite CJD from the National Taiwan University Hospital during the period 1976-1995. It is the largest case series of Chinese CJD up to now. All these patients fulfil the clinical definite diagnosis of CJD proposed by Brown et al. (1986), including rapidly evolving dementia, myoclonus, periodic electroencephalographic (EEG) activity (0.5-2 Hz) and death within 12 months. The clinical characteristics of the present series, including age at onset, sex ratio, duration, initial symptoms, neurological signs, EEG abnormalities, and neuroimaging studies were similar to those reported in other countries. However, there is a high incidence of initial ataxic gait as the presentation in our patients. Eight (57%) out of 14 patients initially had gait ataxia alone or in association with dementia. CJD should be considered in the differential provisional diagnosis of any middle-aged patient with a progressive ataxic syndrome.

Aged↗

PubMed1996

Effects of paraquat on the substantia nigra of the wistar rats: neurochemical, histological, and behavioral studies.

Effects of paraquat on the substantia nigra of the male Wistar rats we re studied pharmacologically by a intracerebral injection of paraquat. The neurochemical, morphological, and behavioral changes observed after a unilateral intranigral injection of paraquat (1-5 microgram) were as follows: (1) neurochemically, paraquat caused dose-dependent depletion of dopamine in the ipsilateral striatum starting 2 weeks after treatment; this effect was long-lasting and irreversible. The ipsilateral striatal dopamine level in animals treated with 3 microgram paraquat was even decreased by 91.5%. (2) Morphologically, 2 microgram of paraquat produced marked loss of Nissl substances and prominent glial reaction in the substantia nigra, while 3 microgram of paraquat caused a severe loss of neurons. (3) Behaviorally, paraquat caused a vigorous rotational behavior in rats contralateral to the lesioned side in response to apomorphine administration (0.5 mg/kg, sc). This effect was dose-dependent and lasted for the entire 16-week experimental period. Taken together, these data indicate that intranigrally injected paraquat may possess marked neurotoxicity and induce degeneration of the rat nigrostriatal dopaminergic system.

Animals↗

PubMed1996

Clinical correlates of quantitative acoustic analysis in ataxic dysarthria.

The speech of 15 Taiwanese patients with cerebellar dysfunction and ataxic dysarthria was investigated utilizing techniques of acoustic analysis and instrumental measurement. Semiquantitative assessment of cerebellar function (SQACF) was also performed. The results of the acoustic analysis of the cerebellar speech were then correlated with the findings in the SQACF. The overlapping of voice onset time highly correlates with truncal ataxia as well as eye movement abnormality and eye-hand coordination. The prolongation of vowel duration also correlates significantly with tandem walking, dysdiadochokinesia and eye movement abnormality. The correlation of the speech function with other cerebellar motor functions provides further insight into the functional anatomy for cerebellar speech motor control. This study concludes that the midline structures-vermis and fastigial nucleus-seem to be the primary focus for the coordination of motor speech in the cerebellum.

Acoustics↗

PubMed1996

Elevated levels of anticardiolipin antibodies and epilepsy in lupus patients.

To examine the association between anticardiolipin (aCL) antibodies and epilepsy, we investigated the serum titers of aCL antibodies in a total 252 systemic lupus erythematosus (SLE) patients recruited in a prospective study. Twenty-one cases with epilepsy which were not attributable to any causes other than SLE were identified after being followed-up for five years. The clinical manifestations were recorded and blood samples were tested for the presence of aCL antibodies (IgG, IgM and IgA isotypes). Among 21 patients with epilepsy, 12 (57.1%), 2 (9.5%) and 2 (9.5%), respectively, had elevated baseline serum levels of IgG, IgM and IgA aCL antibodies. There was a dose-response relationship between risk of seizure and the baseline serum level of aCL antibodies (P < 0.01). The odds ratio of developing seizure were 3.7 for those who had a high level of aCL antibodies compared with those without a detectable level of aCL antibodies as the referent. Our results indicate that epilepsy as a primary neuropsychiatric event among lupus patients is associated with a high titer of aCL antibodies.

Adolescent↗

PubMed1996

Caregiving experiences of family caregivers of elderly persons with dementia in northern Taiwan.

This is part of the follow-up to of a large epidemiological study on the prevalence of dementia. Twenty-nine caregivers of demented elderly persons identified from previous study were further studied in the second phase in order to understand the caregiving experiences. In home, one-time, face-to-face interviews were used to collect data. Qualitative data derived from open-ended questions were transcribed verbatim and the content analyzed by the researchers for major themes. Difficult tasks most frequently reported by caregivers were difficulties in helping with activities of daily living, managing incontinence, and handling patient's health problems. Patient's memory and behavioral problems most frequently causing difficulties in care were suspicion/accusation, forgetfulness, and wandering. Strategies which were most often used by caregivers to handle specific difficult tasks were environmental management and doing/fixing for the elderly subject; to handle patient's memory/behavioral problems were convincing them and going along with them. In overall caregiving strategies, care arrangement was most often used by caregivers. The findings of this study can sensitize the health providers to a wide variety of difficulties and problems caregivers of patients with dementia encounter. Health providers might be also more aware of the different strategies caregivers use in handling these difficulties and problems. Efforts can be put into helping families use more effective strategies when handling the behavioral problems and caregiving difficulties.

Adult↗

PubMed1995

Effects of concanavalin A on desensitization kinetics of GABA responses in Achatina fulica neurons.

The effects of the lectin concanavalin A (Con A), on the kinetics of desensitization of the responses of voltage clamped Achatina fulica LP5 neuron to microperfused acetylcholine (ACh) and GABA were compared. Both ACh and GABA elicited increases in chloride conductance which decayed biphasically during prolonged applications of these agonists; an initial rapid decay was followed by a later slow decay. Con A (5 micrograms/ml) accelerated both the fast and the slow decays of responses to ACh. Con A (5 micrograms/ml) also accelerated the fast decay of responses to GABA, but the slow decay was unaffected, even by 20 micrograms/ml or more of the lectin. It is suggested that, at least in the case of GABA receptor, the fast and slow decays involve distinct desensitization kinetics. The effects of Con A on the desensitization of the ACh and GABA responses were reversed by D-mannose, a competitive and specific inhibitor of Con A binding to membrane sugar residues. These results provide further evidence that receptor desensitization can be influenced by perturbing the sugar moieties associated with the subunits comprising these signalling macromolecules. The carbohydrate residues may play an important role in regulating desensitization of transmitter receptors.

Acetylcholine↗

PubMed1995

Source localization of averaged and single EEG spikes using the electric dipole model.

A scheme for localizing the epileptic focus is proposed. The scheme is on the basis of a model with an electric dipole inside a four-layer inhomogeneous spherical model of head and utilizes a nonlinear programming algorithm applying the gradient projection method. Various initial estimates are used to prove the stability of the implemented dipole model. Fourteen single spike data and the averaged spike data are used to localize the epileptic focus. The results of the usage of the averaged spike data show that the dipole position is compatible with visual inspection of experienced clinical physicians. The results of the usage of the single spike show that 11 of the 14 single spikes have dipole locations near the result of the averaged spike but the estimated dipole moments differ markedly from one another. The localization results of the other three single spikes show that the dipole position is strongly affected by the background EEG. This kind of interference generally causes the eccentricity of the dipole to deviate from its anatomically meaningful value. According to our results, the electric dipole model is concluded to be valuable for the clinical application of localizing epileptic foci.

Algorithms↗

PubMed1995

Evaluation of parametric methods in EEG signal analysis.

In this paper, a well designed database, considering statistical characteristics and including all types of Electroencephalogram (EEG) is built. 900 EEG segments, each with a short interval (1.024 sec) in this database are clustered into eight classes. Three tests of white noise for evaluating the efficiency of autoregressive (AR) and autoregressive-moving average (ARMA) models are proposed. The Akaike information criterion (AIC) is used for determining orders of AR and ARMA models. The AR model requires a higher model order (8.67 on the average) than the ARMA model (6.17 on the average). However, it is found that about 96% of the 900 segments can be efficiently represented by the AR model, and only about 78% of them can be efficiently represented by ARMA model. We therefore conclude that the AR model is preferred for estimating EEG signals.

Algorithms↗

PubMed1995

The value of ultrasound measurement of gallbladder wall thickness in predicting laparoscopic operability prior to cholecystectomy.

We prospectively analysed 51 consecutive cases who underwent laparoscopic cholecystectomy from June 1992 to February 1993. There were 35 cases of chronic cholecystitis and 16 cases of acute cholecystitis. All underwent pre-operative ultrasonography, complete blood cell count, liver function test and endoscopic retrograde cholangiopancreatography. Of those 44 had post-operative ultrasound within the first 2 d and again on the seventh day. In 35 cases of chronic cholecystitis, 31 of 32 cases with a pre-operative gallbladder (GB) wall thickness of less than 6 mm were successfully resected laparoscopically. All three cases with a GB wall thicker than 6 mm were converted to open cholecystectomy. In acute cholecystitis, the wall thickness of the laparoscopic cholecystectomy group ranged from 2 to 9 mm (average 4 mm) and the wall thickness of the conversion group was 4-7 mm (average 6 mm). Post-operative fluid accumulation was noted in 28 (63.6%) cases. There was no correlation between post-operative pyrexia, duration of post-operative pain, clinical complications and the presence of fluid accumulation in the GB fossa. However, of four cases with increasing fluid on the seventh day, three developed complications. We conclude that ultrasonography is valuable in chronic cholecystitis for selecting cases for laparoscopic cholecystectomy.

Adult↗

PubMed1995

A comparison of trial shoe and shell shoe fitting techniques.

In Europe, bespoke orthopaedic shoes are usually sent for a trial fitting in order to check the fit and indicate any modifications required before final finishing. The use of shell shoes at the fit assessment stage, rather than the traditional alternative of partially or fully finished shoes, can offer service advantages, and is widely used for example in the Netherlands. However the comparability of shell fit assessment with the traditional method of trial shoe fit assessment has not been evaluated, either to assess its sensitivity or to elucidate any difference in assessment technique required of the orthotist. In this work, the results of fit assessments by both methods are compared. The trial involved a group of normal subjects wearing high street shoes of styles similar to those used for orthopaedic footwear. The results indicate that the shell fit assessments were in the main comparable to those for trial shoe fit. The only consistent area of deviation noted, in the heel at the topline, is attributable to a construction factor in shoe making. Apart from this area, the orthotist need not adjust his technique to make use of the shell method.

Anthropometry↗

PubMed1995

Laparoscopic cholecystectomy can disseminate in situ carcinoma of the gallbladder.

BACKGROUND: Early case reports suggest more frequent and rapid recurrences of carcinoma of the gallbladder after laparoscopic cholecystectomy (LC) than after open cholecystectomy. This cancer has a poor prognosis and occurs in 1 percent of patients who undergo cholecystectomies. STUDY DESIGN: A recent community hospital series of gallbladder carcinoma (GBC) was reviewed and the total reported experience of GBC after LC was compiled. Diagnostic findings were compared for patients with GBC and a consecutive series of 24 patients who had LC for benign disease. RESULTS: Nine patients with GBC were found among 928 patients who had undergone cholecystectomy (0.97 percent incidence). Compared to patients without GBC, patients with carcinoma were older, had thicker gallbladder walls, and had more abnormalities detected intraoperatively (all p < or = 0.05). Recurrence of GBC occurred more rapidly after LC, and in diffuse peritoneal and port sites when compared with recurrence patterns after open cholecystectomy. CONCLUSIONS: In patients with GBC, LC may be sufficient when the disease is confined to the gallbladder mucosa and the gallbladder is excised intact without bile spillage. However, patients whose gallbladders are torn during dissection or patients who have invasive tumors should undergo laparotomy and local reexcision. In situ GBC can be implanted if the organ is torn during dissection. When gallbladders with suspicious wall thickening or adhesions are noted at LC, especially in older patients, the procedure should be converted to open cholecystectomy.

Aged↗

PubMed1994

Anticardiolipin antisera from lupus patients with seizures reduce a GABA receptor-mediated chloride current in snail neurons.

The effects of circulating anticardiolipin (ACL) antisera in lupus patients on the LP5 central neuron of snail were studied. Both GABA and glutamate increased a chloride conductance of the LP5 neuron. The ACL antisera decreased the GABA-elicited responses in a concentration dependent manner while it had no effect on glutamate-elicited responses. The ACL antisera affected neither the resting membrane current, nor the membrane conductivity of neuron. Antisera without the activity of anticardiolipin did not decrease the GABA-elicited responses. The seizure incidence of the patients with higher ACL antisera levels is also higher. It is concluded that ACL antisera inhibited the GABA ionophore receptor complex in a snail central neuron.

Animals↗

PubMed1994

Interactions of anticholinesterases with Achatina fulica acetylcholine responses and electrogenic sodium pump.

The dose-dependent effects of the anticholinesterases, neostigmine and mycotoxin territrem-B, were determined on: (i) Cl(-)-responses of voltage clamped Achatina fulica neurons to microperfused acetylcholine; (ii) the 4 K(+)-induced outward currents evoked by an electrogenic sodium pump in the same neuron; and (iii) acetylcholinesterase activity of Achatina fulica ganglionic homogenates. Both compounds at low doses potentiated the peak acetylcholine responses. However, they had different effects at higher (> 1 microM) doses in that neostigmine now antagonized acetylcholine responses, while territrem-B still produced a maximal potentiation. At all doses neostigmine produced a dose-dependent inhibition of acetylcholinesterase activity. The cholinolytic effect of high doses of neostigmine was associated with the inhibition of 4 K(+)-induced current in the same neuron, while territrem-B neither altered the K(+)-induced current nor antagonized acetylcholine responses. The cholinolytic effect of neostigmine was completely antagonized by the inhibition of electrogenic sodium pump by ouabain or by perfusion with K(+)-free solution. These results suggest that neostigmine at high concentrations inhibits the electrogenic sodium pump and that the cholinolytic effect of high doses of neostigmine is secondary to this action. Territrem-B, on the other hand, had no effect on the electrogenic sodium pump and had no effect on the neuronal membrane properties other than to inhibit acetylcholinesterase. Thus, territrem-B may be a useful tool for studying the interaction between acetylcholinesterase and acetylcholine receptors.

Acetylcholine↗

PubMed1994

Noninvasive hemodynamic classification of carotid-cavernous sinus fistulas by duplex carotid sonography.

The hemodynamic classification of the CCF has important implications for prognosis and therapy, but satisfactory criteria for such a differentiation are still lacking. We studied the application of extracranial duplex sonography in 14 cases of CCF with emphasis on the hemodynamic parameters of the RI and flow volume and made a correlation with the angiographic findings. We conclude with proposed duplex sonographic criteria for hemodynamic classification: (1) small RI with increased flow volume in the ICA: direct ICA-cavernous sinus fistulas (type A); (2) normal RI and flow volume in the ICA and ECA: dural branch of ICA-cavernous sinus fistulas (type B); (3) small RI with or without increased flow volume in the ECA: dural branch of ECA-cavernous sinus fistulas (type C) or dural branches of ICA- and ECA-cavernous sinus fistulas (type D). Application for assessment of the therapeutic effectiveness was also demonstrated.

Arteriovenous Fistula↗

PubMed1994

Carbon dioxide-enhanced ultrasonography of liver tumors.

CO2 gas-enhanced ultrasonography was performed in 37 patients (47 studies) for the purpose of detecting small tumors and evaluating differential diagnosis. With conventional ultrasonography, 62 lesions were identified in 25 patients with HCC, 13 tumors were identified in eight patients with hemangioma, and multiple tumors were found in four patients with metastatic adenocarcinoma. CO2-enhanced ultrasonography detected five additional hemangiomas, 12 additional nodules in HCC, and the same number of metastatic nodules. The patterns of CO2 enhancement were characterized as homogeneous, heterogeneous, rim, internal spotted, negative, and mixed (more than one pattern in one lesion). The rim enhancement pattern was found to be specific for hemangioma. The internal spotted enhancement pattern was found exclusively in HCC. All the lesions that demonstrated negative enhancement were treated HCC. All the metastatic tumors demonstrated the mixed rim and internal spotted enhancement pattern. We suggest that CO2-enhanced ultrasonography is a useful tool in detecting small liver tumors. It can also help in the differentiation among various hepatic tumors.

Adenocarcinoma↗

PubMed1994

The value of duplex and continuous wave Doppler sonography for evaluation of the extracranial vertebral arteries: a prospective comparison with angiography.

BACKGROUND: The role of duplex sonography in the detection of the extracranial vertebral arteries is not well established. The purpose of this study was to determine the practical possibilities of vascular sonography for non-invasive investigation of the vertebral arteries. METHODS: The extracranial vertebral artery was divided into the pretransverse segment, the intertransverse segment C6-C2, and the atlas loop. The first two segments were examined by duplex probe and the third segment, by continuous-wave probe. Sixty vertebral arteries were studied for detecting vessel diameter, peak systolic as well as diastolic frequency shifts, flow direction and Doppler flow characteristics. A blind angiographic comparison was also performed for the sake of confirming morphological findings and flow direction. RESULTS: Duplex imaging could detect more than 90% of the vertebral arteries. The mean value of vessel diameter was 3.3 +/- 0.6 mm for the right vertebral artery and 3.5 +/- 0.5 mm for the left. Peak systolic as well as diastolic frequency shifts expressed in KHz was 1.4 +/- 0.4 versus 1.6 +/- 0.5 and 0.5 +/- 0.2 versus 0.5 +/- 0.2 in the right and the left vertebral arteries respectively. A 74% agreement in vessel size was obtained by both duplex scanning and angiography. A 100% accuracy was obtained for blood flow direction through means of a Doppler signal. Abnormal findings included stenosis or occlusion (four arteries), hypoplasia or aplasia (two arteries), and subclavian steal phenomenon (two arteries); Six of these eight were correctly predicted by confirmation of the angiographic findings. CONCLUSIONS: A combination of duplex and continuous wave Doppler sonography was affirmed in this study as a relatively accurate screening technique for detection of vertebral artery abnormalities.

Adult↗