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Biomedical subjects

W C Chen

Publications and source records attributed to W C Chen.

At least 163 records · Page 9Linked to original sources
PubMed1991

Factors influencing radiation exposure during the extracorporeal shock wave lithotripsy.

A prospective evaluation of 89 consecutive sessions of extracorporeal shock wave lithotripsy (ESWL) was undertaken to try and find the best way of minimising the amount of exposure to radiation. Forty-two patients were randomly allocated to undergo ESWL treatment by experienced surgeons (group A), and 47 to undergo the treatment by inexperienced surgeons (group B). The mean calculated entrance radiation exposure was 3.01 rads (group A: 2.64 (0.97) rads, range 1.00-4.48, group B: 3.38 (0.86) rads, range 1.11-5.75). Among factors that influenced radiation exposure, the tissue: air ratio should be borne in mind and the level of skill in controlling movement of gantry was the most important in reducing the exposure to radiation.

Adult↗
PubMed1991

Diagnostic value of cerebrospinal fluid immunoglobulin G (IgG) in pediatric neurological diseases.

A total of 71 cerebrospinal fluid (CSF) specimens with paired serum samples from 16 controls and 55 patients with various neurologic diseases ranging in age from 1 to 15 years old were studied using a rate nephelometer to measure their immunoglobulin G (IgG) and albumin levels in both their CSF and serum. The patients included 15 cases of encephalitis, 6 cases of purulent meningitis, 20 cases of aseptic meningitis, 2 cases of multiple sclerosis and 12 cases of other noninflammatory neurologic diseases. The values of the CSF IgG quotient, IgG index, and de novo central nervous system (CNS) IgG synthesis were then calculated for each subject. In the control group, the mean values were as follows: CSF IgG, 1.45 mg/dl; IgG quotient, 6.2%; IgG index, 0.55; and de novo IgG synthesis, -1.17 mg/day. Those with CNS inflammatory diseases had significantly higher CSF IgG levels and IgG quotients compared with controls (p less than 0.05). The IgG index was selectively elevated in cases of encephalitis (p less than 0.005). The values for de novo IgG synthesis showed significant increase in all types of CNS inflammatory diseases except for the group with aseptic meningitis. In the noninflammatory diseases, none of the CSF parameters revealed any significant differences from those of the control group. Six cases (40%) of encephalitis showed normal CSF protein value, but an abnormal IgG component, IgG index and de novo IgG synthesis. Quantitation of IgG and other derivatives in CSF gives a sensitive supplementary reference for the detection of CNS infection.

Adolescent↗
PubMed1991

[Scavenging of probimane on semiquinone free radical formation by doxorubicin in rat heart].

Probimane, dl-bis (4-morpholin-methyl 3,5-dioxopipweazin-1-yl) propane first synthesized in China, is a dioxopiperazin compound with antineoplastic, antimetastatic and radiopotentiating activities. In order to evaluate the mechanisms of cardiotoxicity protective action of probimane, the free radical induced by doxorubicin were analysed by electron spin resonance (ESR) techniques. Our studies showed that doxorubicin stimulated the formation of semiquinone free radicals in the rat heart homogenate and heart cell mitochondria systems, and probimane inhibited the free radical formation in both systems, with the dose-dependent and time-dependent responses. The inhibitory rates of doxorubicin free radical formation in rat heart homogenate system by probimane 0.6 mmol.L-1 at time of 3, 5, 10, 15, 30, 45 and 60 min were 44.6%, 43.0%, 51.5%, 74.3%, 68.1%, 56.1% and 39.9% respectively. The inhibitory rates of semiquinone free radical formation in mitochondria system by probimane at the concentration of 0.02, 0.06, 0.6, 1.2 and 2.4 mmol.L-1 were 17.07%, 29.87%, 63.95%, 64.62% and 83.64%, respectively. Probimane had no effect on NADH2, but inhibited NADH dehydrogenase activity at higher concentration.

Animals↗
PubMed1990

Polycystic kidney of autosomal dominant inheritance, polycystic liver and congenital hepatic fibrosis in a single kindred.

A family with clear evidence of concomitant congenital hepatic fibrosis, polycystic liver and adult-type polycystic kidney is reported. The autosomal dominant inheritance of polycystic kidney in association with either liver cyst or hepatic fibrosis in this family suggests that various combinations of hepatic and renal fibrocystic lesions are possible to occur. Additionally, in the proband a very rare association of congenital hepatic fibrosis and cerebral aneurysm was present.

Adult↗
PubMed1990

Pulmonary infarction presenting as aseptic cavitation.

A case of pulmonary infarction presenting as aseptic cavitation was reported. Basically, the patient suffered from rheumatic heart disease, mitral stenosis and insufficiency, and atrial fibrillation with predominant right heart enlargement. Hemoptysis, chest pain and dyspnea were present. Chest film simulated a thin wall lung abscess. The clinical picture suggested aseptic cavitation, which was confirmed by 99mTc-MAA lung scan.

Aged↗
PubMed1990

Retroperitoneal abscesses.

Abscesses developing within the retroperitoneal spaces are complicated serious surgical infections marked by an insidious, occult process lead to considerable mortality and morbidity. In a retrospective review of 39 retroperitoneal abscesses in our hospital. Attention is directed to clinical presentation, diagnosis and treatment. On average, 19.2 days was required to establish the diagnosis and overall mortality is 7.7%. Two patients suffered from complications of discharged sinus and recurrent abscess respectively. Computed tomography (CT) is thought to be the best diagnostic modality of retroperitoneal abscesses. Only 2 patients (5.3%) shows bilateral lesions. Detailed anatomic reviews detailing the pathogenesis of bilateral retroperitoneal abscess are also discussed.

Abscess↗
PubMed1988

Atrial tachycardia, 2:1 alternate Wenckebach periodicity, and atrial standstill.

A case of atrial tachycardia, 2:1 alternate Wenckebach periodicity and atrial standstill is reported in an 80-year-old woman who complained of exertional dyspnea and occasional syncope for two years. Two blocked P' waves appeared after each Wenckebach period suggesting type B alternating Wenckebach phenomenon (Mobitz type II 2:1 A-V block distal, and Wenckebach conduction proximal).

Aged↗
PubMed1988

Complete atrioventricular block, retrograde atrial activation and intra-atrial block.

A case of complete atrioventricular block, retrograde atrial activation, and intra-atrial block was reported. Inhomogeneous inhibition of the atrioventricular junction and the so-called summation of impulses may both act together to make retrograde conduction possible when third-degree atrioventricular block was present. In lead 2, P waves were dome-shaped, and in lead V1, P waves were biphasic; narrow and peaked P waves intermittently appeared, denoting third-degree intra-atrial block. The peaked P waves signified that the right atrium was activated while the left atrium was not depolarized.

Atrioventricular Node↗
PubMed1987

1,25-Dihydroxyvitamin D3-mediated inhibition of human B cell differentiation.

We have examined the mechanisms of 1,25-dihydroxyvitamin D3 (D3)-mediated inhibition of human B cell differentiation to immunoglobulin (Ig) secreting cells. B lymphocytes were purified from human tonsils and peripheral blood mononuclear cells. Mononuclear cells were separated into adherent cells and nonadherent cells. Cells were stimulated with Staphylococcus aureus Cowen I (SAC) or pokeweed mitogen (PWM) for 7 days and immunoglobulin production was measured by ELISA assay, 1,25-dihydroxyvitamin D3 was added at different times during cultures. 1,25-Dihydroxyvitamin D3, in a dose-dependent manner, inhibited both SAC and PWM-induced Ig production by mononuclear cells. The maximum inhibition was observed when 1,25-dihydroxyvitamin D3 was added at the beginning of culture, but inhibition could still be observed when 1,25-dihydroxyvitamin D3 was added on day 4 of cultures. The inhibitory effect of 1,25-dihydroxyvitamin D3 on Ig production was significantly greater on mononuclear cells than on nonadherent cells. Addition of in vitro purified IL-1 to nonadherent cells enhanced 1,25-dihydroxyvitamin D3-induced inhibition of Ig production. 1,25-Dihydroxyvitamin D3 also inhibited the expression of IL-2 receptors on B cells activated with SAC. 1,25-dihydroxyvitamin D3 did not inhibit Ig production by SAC preactivated B cell blasts in response to T cell supernatants. These data suggest that vitamin D3 inhibits Ig production by inhibiting IL-2 receptor expression on B cells and via its effect on adherent macrophages. Vitamin D3 does not influence the effect of differentiation factors on activated B cells that have already expressed growth/differentiation factor receptors.

Adult↗
PubMed1987

Computed tomography of a meniscal cyst.

A meniscal cyst of the knee is a rare lesion, and a palpable large meniscal cyst is even more rare. This article suggests that CT scan demonstrates clear location, size, contents, and connection of the cyst with meniscus and peripheral tissue. By a combination of arthrography and CT scan, detection of the cysts in zone 3 (parameniscal area) is possible with ample demonstration of whether the cyst is associated with a meniscal tear. This provides a guideline in determining the treatment of the lesion.

Adult↗
PubMed1986

Application of a new spatial signal averaging device for the beat-to-beat detection of cardiac late potentials.

A new high resolution digital signal averaging device was developed to record precordial late potentials. The subjects examined included 8 normals (including medical patients with normal cardiovascular status), and 21 patients with coronary artery disease (CAD) and myocarditis of probable viral origin. Late potentials were evident in 11 cases (CAD 8 cases and myocarditis in 3 cases). In 10 patients, multiple ventricular premature beats and in 3 others, attacks of ventricular tachycardia had been present. Sudden cardiac death occurred later in one patient. It was concluded that late potentials as recorded by this simple new device are predictive of ventricular arrhythmias--sometimes life threatening. As no triggering is necessary, both conventional and beat-to-beat signal averaging can be carried out and the presence of various arrhythmias is negligible.

Adult↗
PubMed1986

The kinetics of dissolution of tooth enamel--a constant composition study.

The kinetics of dissolution of powdered bovine enamel and of human enamel, both untreated and extracted with either hypochlorite or chloroform, has been studied using a constant solution composition technique in undersaturated solutions of calcium phosphate (total molar calcium concentration, TCa = 0.3 to 13.1 X 10(-3) mol L-1, total molar phosphate, Tp = 0.18 to 7.9 X 10(-3) mol L-1) at an ionic strength of 0.15 mol L-1, and pH = 4.5. The kinetic equations describing the dissolution reactions suggest a surface dislocation mechanism, and the presence of fluoride ion markedly retarded the reaction. For human enamel, a fluoride level of only 0.5 ppm reduced the rate of dissolution ten-fold. In contrast, the dissolution of hydroxyapatite, HAP, is best interpreted in terms of a polynucleation process.

Animals↗
PubMed1986

Clinical significance of bifid T waves.

An attempt was made to analyze bifid T waves which appeared in different clinical conditions. Bifid T waves occurred in 16% of 600 normal children, 92% of 37 cases of childhood ventricular septal defect (VSD), 6 of 10 cases of tetralogy of Fallot (children) and 33% of 193 patients with cerebrovascular accidents (including 3 children). Sixteen cases of bifid T waves which appeared after amiodarone treatment were also analyzed. It was thought that in normal children, bifid T waves might be due to right ventricular preponderance. In VSD, the bifid T waves assumed a peculiar "dome and dart" appearance. In cerebrovascular accidents, autonomic imbalance might be at fault. In cases of treatment with adriamycin, myocardial toxicity is the most probable cause. The conclusion was made that bifid T waves can appear in different clinical settings, which must be considered individually.

Adult↗