Biomedical subjects

Y C Chang

Publications and source records attributed to Y C Chang.

At least 217 records · Page 12Linked to original sources

PubMed1995

An analysis of fetal hemoglobin variation in sickle cell disease: the relative contributions of the X-linked factor, beta-globin haplotypes, alpha-globin gene number, gender, and age.

Five factors have been shown to influence the 20-fold variation of fetal hemoglobin (Hb F) levels in sickle cell anemia (SS): age, sex, the alpha-globin gene number, beta-globin haplotypes, and an X-linked locus that regulates the production of Hb F-containing erythrocytes (F cells), ie, the F-cell production (FCP) locus. To determine the relative importance of these factors, we studied 257 Jamaican SS subjects from a Cohort group identified by newborn screening and from a Sib Pair study. Linear regression analyses showed that each variable, when analyzed alone, had a significant association with Hb F levels (P < .05). Multiple regression analysis, including all variables, showed that the FCP locus is the strongest predictor, accounting for 40% of Hb F variation. beta-Globin haplotypes, alpha-globin genes, and age accounted for less than 10% of the variation. The association between the beta-globin haplotypes and Hb F levels becomes apparent if the influence of the FCP locus is removed by analyzing only individuals with the same FCP phenotype. Thus, the FCP locus is the most important factor identified to date in determining Hb F levels. The variation within each FCP phenotype is modulated by factors associated with the three common beta-globin haplotypes and other as yet unidentified factor(s).

Adolescent↗

PubMed1995

Subclinical neurotoxicity of mercury vapor revealed by a multimodality evoked potential study of chloralkali workers.

Pattern visual, brainstem auditory, and somatosensory evoked potential (EP) studies were performed on 26 chloralkali workers. The intensity of mercury vapor exposure in these workers was estimated from the individual working history. Mercury levels in blood, urine, and hair were determined with atomic absorption spectrometry. The EP findings were compared with those from individually matched normal subjects. In brainstem auditory and somatosensory EP studies, prolonged neural conduction times in the central nervous system (CNS) were found in workers exposed to mercury vapor. In the pattern visual EP study, mercury workers had higher interpeak amplitudes. Findings of this study suggested that chronic exposure to mercury vapor would affect the CNS functions. A multimodality EP study is a useful adjunct in evaluation of chronic mercury neurotoxicity, especially in an epidemiological study.

Adult↗

PubMed1995

Overexpression of P-glycoprotein in untreated AFP-producing gastric carcinoma.

P-glycoprotein (P-gly), which is responsible for the phenotypic expression of multidrug resistance in cancerous tissue was stained immunohistochemically in previously untreated alpha-fetoprotein (AFP)-producing (n = 20) and nonproducing gastric cancers (n = 20). P-gly, AFP, and carcinoembryonic antigen(CEA) were stained in formalin-fixed paraffin-embedded tissue sections immunohistochemically using the monoclonal antibody JSB-1, anti-AFP, and anti-CEA, respectively. DNA ploidy pattern was determined by Fluorescence Activated Cell Sorter (FACS) analyzer. P-gly was significantly overexpressed in AFP producing gastric cancers (60%) than in AFP nonproducing ones (20%) (P < 0.01). When the result of P-gly staining was analyzed among the AFP-positive cases, P-gly positivity did not emerge either as a significant prognostic factor or as a predictor of the metastatic potentiality of the tumor. The intrinsic overexpression of P-gly in AFP producing gastric cancers proves its biological and morphological similarities to hepatocellular carcinoma. The significantly (P < 0.05) higher incidence of P-gly in diploid tumors indicate that expression of this phenotype might be related to the differentiation of the tumor. P-gly was overexpressed in AFP producing gastric carcinoma and the existing drug resistance, frequent recurrence, and poor prognosis might be explained by presence of P-gly in this carcinoma.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1995

Effect of postischemic reperfusion on microcirculation and lipid metabolism of skeletal muscle.

To study the effect of ischemia reperfusion injury on microvascular reactivity and tissue metabolism in skeletal muscle, a Sprague-Dawley rat cremaster muscle was prepared as a tourniquet ischemia model and subjected to 2 hr ischemia followed by 1 hr reperfusion to simulate the timing of ischemia during microvascular surgery. The dose-response curve of arteriolar reactivity to norepinephrine, lipid peroxidation, and ultrastructure of capillaries was determined in both the control and postischemic reperfusion stages. Judging from the results, we summarize our observations as follows: (1) Postischemic reperfusion significantly increased arteriolar reactivity to norepinephrine, in which the EC50 for vasoconstriction decreased in all three orders of arterioles. These results suggest that reperfusion could have impaired the vasodilation control mechanism, possibly being endothelium dependent. (2) Lipid peroxidation increased sixfold in the reperfusion group, suggesting that oxygen free radicals have produced significant tissue damage under the created conditions. (3) Significant endothelial damage in the capillaries shown by electron microscope observation supports these studies, indicating that ischemia/reperfusion in clinically transplanted skeletal muscles could cause significant damage to the tissue microcirculation both physiologically and metabolically.

Animals↗

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

Surface modifications of alginate/poly(L-lysine) microcapsular membranes with poly(ethylene glycol) and poly(vinyl alcohol).

Three different surface modifications were conducted on the membranes of double-layer alginate/poly(L-lysine) microcapsules with tosyl chloride-activated poly(ethylene glycol), cyanuric chloride-activated poly(ethylene glycol) and tosyl chloride-activated poly(vinyl alcohol), separately. All these surface modifications strengthen the microcapsular membranes. Of the three surface-modified microcapsules, those treated with cyanuric poly(ethylene glycol) and tosylated poly(vinyl alcohol) have mechanical strength higher than that treated with tosylated poly(ethylene glycol). The permeabilities of the proteins were only slightly affected by the surface modifications. When IW32 erythroleukaemia cells were entrapped inside these microcapsules, cells proliferated to a density of (1.0-1.5) x 10(7) cells cm-3 after 7 d culturing compared with 2 x 10(6) cells cm-3 attained by free cell culturing. The intracapsular concentration of erythropoietin which was secreted by the IW32 cells accumulated to concentrations of 5-7 U cm-3. In addition, 3T3 cells were found to have a very low tendency to attach to the microcapsular membranes of all three surface-modified preparations.

3T3 Cells↗

PubMed1995

Neurophysiologic studies and MRI in Pelizaeus-Merzbacher disease: comparison of classic and connatal forms.

Four patients with the classic form and 1 patient with the connatal form of Pelizaeus-Merzbacher disease were studied with magnetic resonance imaging, electroencephalography, and multimodal evoked potentials, including brainstem auditory evoked potentials, somatosensory evoked potentials, and visual evoked potentials. Comparisons between these findings were made. It was determined that the neurophysiologic studies, particularly brainstem auditory evoked potentials, are of value in early diagnosis of Pelizaeus-Merzbacher disease; brainstem auditory evoked potentials with only normal wave I may be a relatively reliable clue suggesting the classic form of Pelizaeus-Merzbacher disease in patients with nystagmus and chronic progressive encephalopathy. Magnetic resonance imaging allows an accurate assessment of the degree of hypomyelination; however, the clinical severity of various forms of Pelizaeus-Merzbacher disease seemed to be independent of the age of onset and the amount of residual myelin. The following may be distinguishing features between the connatal and classic forms of Pelizaeus-Merzbacher disease: hypoplasia of the cerebellum and brainstem, and diffuse brain atrophy on magnetic resonance imaging; optic atrophy with abnormal visual evoked potential; seizure disorder with abnormal electroencephalography, and/or auditory nerve impairment with abnormal wave I of brainstem auditory evoked potentials in the early stage of the disease.

Adult↗

PubMed1995

Renal tubular acidosis complicated with hypokalemic periodic paralysis.

Three Chinese girls with hypokalemic periodic paralysis secondary to different types of renal tubular acidosis are presented. One girl has primary distal renal tubular acidosis complicated with nephrocalcinosis. Another has primary Sjögren syndrome with distal renal tubular acidosis, which occurs rarely with hypokalemic periodic paralysis in children. The third has an isolated proximal renal tubular acidosis complicated with multiple organ abnormalities, unilateral carotid artery stenosis, respiratory failure, and consciousness disturbance. The diagnostic evaluation and emergent and prophylactic treatment for these three types of renal tubular acidosis are discussed.

Acidosis, Renal Tubular↗

PubMed1995

Metabolism of daidzein and genistein by intestinal bacteria.

The isoflavones daidzein [1] and genistein [2] were fermented with human fecal bacteria under anaerobic conditions. Dihydrodaidzein [3], benzopyran-4,7-diol,3-(4-hydroxyphenyl) [4], and equol [5] were isolated from the fermentation broth of 1. Only one metabolite, dihydrogenistein [6], was isolated and characterized from the fermentation broth of 2. Metabolites 3-6 were identified by spectral methods.

Bacteria↗

PubMed1995

Metabolites of daidzein and genistein and their biological activities.

A number of metabolites of daidzein and genestein have been synthesized and their biological activities determined. Equol [3], 5,7,4'-trihydroxyisoflavan [5], 4,7,4'-trihydroxyisoflavan [6], dihydrodaidzein [8], and dihydrogenistein [9] were synthesized either from daidzein [1] or genistein [2] by hydrogenation. Similarly, the derivatives 4, 7, and 11 were synthesized from 3, 6, and 10, respectively. During acetylation and nmr experiments, 9 was converted to a novel enol intermediate [10]. Antifungal, antibacterial, mosquitocidal, nematocidal, and topoisomerase inhibition activities of these compounds were evaluated, with equol [3] being the most active of the compounds tested against topoisomerase I.

Acetylation↗

PubMed1995

Survey of public awareness, understanding, and attitudes toward epilepsy in Taiwan.

A survey of public awareness and understanding of and attitudes toward epilepsy was made in Taipei City and Chin-San Village, Taiwan in 1992. In a population sample of 2,610 adults, 87% had read or heard about epilepsy, 70% knew someone who had epilepsy, 56% had seen someone having a seizure, 18% would object to having their children associated with persons with epilepsy, 72% would object to having their children marry a person with epilepsy, 31% believed that epileptic persons should not be employed in jobs as other persons are, 7% believed that epilepsy was a form of insanity, 34% did not know the cause of epilepsy, 13% did not know what an epileptic attack was like, and 18% did not know what to recommend if their friends or relatives had epilepsy. Youth, higher education, and upper levels of employment were correlated with answers that were more favorable concerning epilepsy in all survey questions except for the question regarding marriage, for which the reverse was noted. The attitudes toward epilepsy disclosed by this study were more favorable than those detected in a similar survey conducted in Henan Province, China. The comparison suggests that the exposure to Western culture and socioeconomic system in Taiwan might have helped reduce the discrimination against epilepsy.

Age Factors↗

PubMed1995

Type IV hyperlipoproteinemia and moderate instability of CAG triplet expansion in the androgen-receptor gene. Lipid, sex hormone and molecular study in a Chinese family with Kennedy-Alter-Sung disease.

Kennedy-Alter-Sung (KAS) disease in a hereditary lower motor neuron disease. In this study, we investigate 2 KAS patients presenting with progressive muscle weakness and wasting, action tremor, perioral fasciculation and gynecomastia. Three carriers and 5 healthy members from this 3-generation KAS Chinese family and 60 normal Chinese controls were included in this study. Hormone studies revealed normal serum level in thyrotropin, prolactin, testosterone, leuteinizing hormone, follicle stimulating hormone, and estradiol. Lipid study disclosed type IV hyperlipoproteinemia in 2 KAS patients and 3 healthy members. Molecular studies revealed that the number of CAG triplet repeats in the first exon of androgen receptor gene of the normal allele is in the range of 15-19 and 12-25 in this family and normal controls, respectively. However, the number of CAG repeat of androgen receptor gene were unstable in the mutant alleles with a range of 41-45 and increased from generation to generation (genomic anticipation) in the 2 KAS patients and 3 female carriers. We conclude that the CAG triplet repeats in mutant allele were unstable in the family with the KAS disease. Furthermore, type IV hyperlipoproteinemia may be a co-transmitted syndrome in the family with KAS disease.

Alleles↗

PubMed1995

Combined electroneurographic and electromyographic studies in lead workers.

OBJECTIVES: To evaluate the effects of chronic exposure to lead on the peripheral nervous system in lead workers. METHODS: Nerve conduction velocity and electromyographic studies were performed on 31 lead workers of a battery recycling factory and 31 sex and age matched controls. 25 cases with mild distal extensor weakness of the upper limbs were classified as the lead neuropathy subgroup and the rest of the lead workers as the lead exposure subgroup. Blood lead concentrations and haematological and biochemical data were recorded. An index of cumulative exposure to lead was calculated by the summation of multiplying the average blood concentration of lead with the duration of exposure at various jobs. RESULTS: Compared with the control group, the distal motor latency of the median nerve was significantly prolonged in the lead neuropathy subgroup, but not in the exposure subgroup. Only six of 31 workers had nerve conduction abnormalities, whereas electromyographic evidence of denervation was found in 93.5% of the lead neuropathy subgroup and 83.5% in the lead exposure subgroup. The electromyographic abnormalities found were neurogenic polyphasic waves in all 29 workers with abnormal electromyographic findings (grade in seven cases and grade ++ in the rest). Spontaneous activity was only recorded in seven workers, with grade + in four and grade ++ in three. There was a positive linear correlation between the index of cumulative exposure to lead and the distal motor latencies of the tibial nerve as well as a negative correlation with conduction velocities of the sural nerve after multivariate analysis and control of potential confounding by age and sex. No correlation could be found between the electrophysiological values and a simple duration of exposure or concentration of blood lead. A non-parametric analysis showed that there was a trend of higher index of cumulative exposure to lead with more severe electromyographic changes. Electromyographic abnormality also occurred in workers with blood lead concentrations between 17.4 and 58 micrograms/dl. CONCLUSION: Electromyographic study in the distal extensors of the upper limbs may be used as a tool for biological monitoring of effect in lead workers.

Adult↗

PubMed1995

Repeated hepatic dearterialization for unresectable liver metastases from gastric cancer: review of five cases.

A novel method of repeated hepatic dearterialization was evaluated in five patients with multiple metastases from gastric cancer in both hepatic lobes. After gastrectomy with extensive lymph node dissection (R2/3), all patients underwent implantation of a vascular occluder around the hepatic artery. Cannulation of the hepatic artery was added for later chemotherapy. The hepatic artery was occluded repeatedly for 1 hour twice daily in combination with intrahepatic infusion of anticancer drugs for as long as possible. Three of five patients demonstrated marked tumour regression with unexpectedly long survival (16 months in two patients and one still alive at 15 months). Carcinoembryonic antigen (CEA) levels decreased to almost normal in four patients who had initially high levels. The present experiences seems to indicate that long survival can be hoped for in patients with advanced gastric cancer with unresectable liver metastases.

Aged↗

PubMed1995

Cumulative injury rate and potential workdays and salary lost.

OBJECTIVES: The purpose of this study was to examine alternative methods for quantifying occupational injuries and to estimate the costs of foregone earnings due to these injuries. METHODS: A model based on the three possible outcomes of occupational injuries (premature death, permanent disability, and temporary dysfunction) was proposed, and several new indices were developed to measure the frequency and severity of occupational injuries. In the calculations, the human capital method was employed to measure potential salary lost due to occupational injury. An example was adopted from a steel corporation to demonstrate these indices. RESULTS: The cumulative injury rates, based on age and duration of employment, represented the average cumulative risk of acquiring occupational injuries by lifetime work duration and by employment duration, respectively. The severity index revealed the rate of estimated potential workdays lost by incorporating both the age at which an injury occurred and the severity weighting factors of various disabilities into the formula. After the estimated potential workdays lost was divided by the total employees' potential affordable workdays, the proportion of potential workdays lost showed a result that adjusted for the varied age distribution in each year implicitly. The potential loss in salary calculated the foregone earnings of occupational injuries, which could be considered as a lower limit of the monetary cost estimated by the willingness-to-pay method. CONCLUSIONS: Such indices supplement disabling frequency and severity rates. They cannot only be applied to occupational safety monitoring, but also to the policy-making process in occupational safety and health.

Adult↗

PubMed1995

Left ventricular thrombi in children with dilated cardiomyopathy.

To define the nature and course of left ventricular (LV) thrombi in pediatric patients, the charts and echocardiographic records of 32 pediatric patients with dilated cardiomyopathy from 1986 to 1991 were retrospectively reviewed. Five patients who were identified according to echocardiographic evidence of LV thrombi fulfilled the criteria of dilated cardiomyopathy. Systemic embolization occurred in three patients with LV thrombi who invariably died despite anticoagulant treatment. Although it was not statistically significant, patients with LV thrombi tended to have a lower ejection fraction compared to patients without LV thrombi. The morphology of LV thrombi in patients with systemic embolization showed nonprotruding features. Thus, children with dilated cardiomyopathy are at risk of developing LV thrombi and systemic embolization. Although it was not possible to identify the risk factors, the risk of developing LV thrombi and systemic embolization may be higher in patients with lower ejection fraction of the left ventricle.

Adolescent↗

PubMed1995

Doppler echocardiography for detection of ventriculo-coronary communication: report of a case.

Ventriculo-coronary communication is frequently encountered in pulmonary atresia patients who have an intact ventricular septum. Preoperative documentation is important to decide the feasibility of right ventricular decompression procedure. Experience of Doppler echocardiographic visualization of this anomaly in a case of critical pulmonary stenosis with intact ventricular septum is reported. Doppler echocardiography is a promising method of detection and should be used in every patient with a high-pressured hypoplastic ventricle before intervention.

Coronary Vessel Anomalies↗

PubMed1995

Female genital tuberculosis: report of seven cases.

Seven cases of histologically proven genital tuberculosis (TB) encountered at the National Taiwan University Hospital in the past 16 years were reviewed. From a total of 54,576 gynecologic specimens submitted for pathologic examination, the occurrence of genital TB was 0.01%. Of these seven patients, one suffered from primary infertility and one from secondary infertility. The patient with primary infertility had been married for 29 years. The patient with secondary infertility underwent a tuboplasty due to bilateral hydrosalpinx. Genital TB was not diagnosed preoperatively in any of the seven cases. The preoperative diagnoses included: postmenopausal spotting, ovarian malignancy, cervicitis, ectopic pregnancy and hydrosalpinx with secondary infertility. This review suggests that genital TB is becoming rare in Taiwan. It is difficult to diagnose from clinical symptoms and is usually discovered on pathologic examination.

Adult↗