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Biomedical subjects

T C Chang

Publications and source records attributed to T C Chang.

At least 127 records · Page 7Linked to original sources
PubMed1994

Regulation of the expression of alkaline phosphatase in a human breast-cancer cell line.

Treatment of the cultured human breast-cancer cells BC-M1 with dexamethasone induced a placental-type alkaline phosphatase (ALP). Both the ALP activity and the mRNA level in the cells were increased. The induction of ALP activity by dexamethasone was time- and dose-dependent. The accumulation of ALP mRNA was inhibited by both actinomycin D and cycloheximide, indicating that its induction is a complex event and may involve other regulatory proteins. Retinoic acid showed opposing effects with dexamethasone on the expression of alkaline phosphatase. Retinoic acid (RA) and phorbol 12-myristate 13-acetate also substantially reduced the dexamethasone-induced expression of ALP. Studies on thermostability and sensitivity to various amino acid inhibitors indicated that the BC-M1 ALP is most similar to the placental form. Northern hybridization analysis also revealed that ALP mRNA transcripts in BC-M1 and term placenta are similar in size and are distinct from that of the placental-like mRNA transcript in choriocarcinoma cells. Analysis of the degradation of BC-M1 ALP mRNA showed a similar half-life of 27 h in the untreated and in dexamethasone- or RA-treated cells. These findings demonstrated that the induction of ALP in BC-M1 cells by dexamethasone is mainly due to the increase in the transcription of the ALP gene.

Alkaline Phosphatase↗
PubMed1994

TSH and TSH receptor antibody-binding sites in fibroblasts of pretibial myxedema are related to the extracellular domain of entire TSH receptor.

The role of TSH receptor antibodies in the pathogenesis of pretibial myxedema is still unclear. This study was designed to determine whether patients with pretibial myxedema had higher serum titers of TSH receptor antibodies, and whether there were TSH and TSH receptor antibody-binding sites on plasma membranes of fibroblasts derived from the skin of pretibial myxedema. If there were, were the binding sites similar to the TSH receptor? The TSH receptor antibodies were determined with radioreceptor assay in 20 normal subjects, 18 hyperthyroid Graves' disease patients without ophthalmopathy, 26 hyperthyroid Graves' disease patients with ophthalmopathy, and 11 patients with pretibial myxedema associated with Graves' ophthalmopathy. TSH and TSH receptor antibody-binding sites were studied on plasma membranes of fibroblasts cultured from the skin of pretibial myxedema with radioreceptor assay. RNA was also extracted from the fibroblasts of pretibial myxedema and reverse transcribed using random primers as the primers for cDNA synthesis. The resulting cDNAs were subjected to amplification by polymerase chain reaction with the use of a set of primers spanning the 5' region (+256/+275 and +616/+635) and the 3' region (+1819/+1838 and +2405/+2424) of the TSH receptor cDNA (+1 transcription start codon). They were further identified by Southern blot hybridization, with the probe spanning the 5' region (+272/+612) and the 3' region (+1908/+2268) of the TSH receptor cDNA (+ 1 transcription start codon), and sequencing. The results showed that patients with pretibial myxedema had higher titers of TSH receptor antibodies in the serum. TSH and TSH receptor antibody-binding sites were present on plasma membranes of fibroblasts derived from the skin of pretibial myxedema patients and related to the extracellular domain of the TSH receptor. These data suggest a common antigenic site in the skin and in the thyroid as a putative target for TSH receptor antibodies or lymphocytes of Graves' disease.

Adult↗
PubMed1994

Prediction of perinatal morbidity at term in small fetuses: comparison of fetal growth and Doppler ultrasound.

OBJECTIVE: To compare fetal growth assessed by ultrasound (change in standard deviation score of abdominal circumference and estimated fetal weight) during the third trimester with predelivery ultrasound measurements of fetal size and Doppler measurements from the umbilical and fetal arteries in order to predict suboptimal perinatal outcome in small babies at term. DESIGN: Prospective observational study. SETTING: Day assessment unit in a university hospital. SUBJECTS: One hundred and four consecutive women with a clinical suspicion of a small fetus during the third trimester confirmed by ultrasound (abdominal circumference below the 10th centile) and ultimately delivered at term. MAIN OUTCOME MEASURES: Acidaemia at birth, fetal distress requiring emergency caesarean section in labour, admission to the neonatal intensive care unit. RESULTS: Ninety-four babies (90%) weighed less than the 10th centile and the incidence of suboptimal perinatal outcome was 27%. The largest areas under the receiver operating characteristic curves for suboptimal perinatal outcome were obtained with the change in standard deviation score of abdominal circumference and estimated fetal weight, and the ratios of aortic/middle cerebral and renal/middle cerebral pulsatility index. Although low, the odds ratios of the change in estimated fetal weight standard deviation score and the Doppler ratios were significantly different from zero. CONCLUSION: Ultrasound assessment of fetal growth and predelivery fetal Doppler pulsatility index ratios were superior to predelivery estimates of fetal size and umbilical artery pulsatility index in predicting suboptimal perinatal outcome in small fetuses delivering at term, although the clinical value of such a prediction may be limited.

Acidosis↗
PubMed1994

Recent advances in the use of Doppler waveform indices in the antenatal assessment of intrauterine growth retardation.

Doppler ultrasound has been advocated as a useful tool to evaluate pregnancies with intrauterine growth retardation (IUGR). However, many previous studies have used smallness for gestational age (SGA) at birth to define IUGR. The ability of Doppler ultrasound to predict SGA, neonatal morphometric indices of wasting such as a low ponderal index, and perinatal morbidity is reviewed. Doppler assessment of the umbilical and uteroplacental vasculatures were inferior to ultrasound measurements of fetal size in the prediction of SGA. In low risk fetuses, umbilical artery waveform indices were of limited value in the prediction of neonatal morphometric indices of wasting. Within a group of high risk fetuses, Doppler assessment of the umbilical artery and, in particular, the middle cerebral and aortic vessels, were useful in predicting fetuses with neonatal wasting. Similar findings were noted in the prediction of perinatal morbidity. The review confirms the usefulness of umbilical artery Doppler waveform indices in the antenatal assessment of IUGR. Whilst preliminary studies appear to suggest that Doppler waveform indices of the middle cerebral and aortic vessels may confer an additional advantage in the antenatal assessment of IUGR, randomized controlled trials evaluating their effect on perinatal outcome and studies on the reproducibility of these indices need to be carried out before their widespread introduction into obstetric practice.

Cerebral Arteries↗
PubMed1994

Relationship of eye movement to computed tomographic findings in patients with Graves' ophthalmopathy.

To elucidate the relationship between eye movement and computed tomographic findings, 101 patients with Graves' ophthalmology were studied. Eye movements were scaled 0 to 3 according to movability. Extraocular muscle width and area were calculated from the largest portion of each muscle from the orbital coronal CT sections. Muscle widths were measured manually and muscle areas were calculated by a digitizer. The width and area of each rectus muscle were significantly correlated with limitation of eye movement. The muscle widths and areas were also significantly correlated to each other (r = 0.91 to 0.77, p < 0.001). Limitations of supraduction and abduction from enlargement of the inferior and medial rectus muscles were the most common clinical findings (46.5% and 39.6%, respectively). In conclusion, this study establishes a relationship between limitation of eye movement and extraocular muscle enlargement. Calculation of the width from the largest portion of the muscle manually from orbital coronal section is a simple method for clinical assessment of the severity of extraocular muscle involvement.

Adolescent↗
PubMed1994

Enzyme capture assay for rapid identification of Escherichia coli in blood cultures.

An enzyme capture assay (ECA) for rapid identification of Escherichia coli in blood cultures by using beta-D-glucuronidase as a marker was developed. Microdilution plates coated with antiglucuronidase were used to capture this enzyme from the cell lysates of blood cultures which showed growth of gram-negative bacteria. The assay, using 4-methylumbelliferyl-beta-D-glucuronide as a fluorogenic substrate, had a detection limit of 0.1 ng/ml (3 x 10(-13) M) for the enzyme; this was approximately equal to a cell concentration of 10(6) CFU of E. coli per ml. Among 212 blood cultures showing growth of gram-negative bacteria, 77 specimens were found to contain E. coli by conventional culture procedures and 73 samples were positive by ECA. Among the 135 blood cultures from which E. coli was not isolated, ECA gave one false-positive (Salmonella enteritidis) reaction. Thus, the sensitivity and specificity for the identification of E. coli in blood cultures by ECA were 94.8% (73/77) and 99.3% (134/135), respectively. From the finding of positive growth in the culture bottle, the assay can be completed within 4 h. In view of the high rate of isolation of E. coli from bacteremic patients, the test can be performed in parallel with conventional culture protocols; this may shorten the identification time for E. coli, and proper antimicrobial treatments may be started 24 h earlier than when results of conventional identification systems are used.

Antibodies, Bacterial↗
PubMed1994

Umbilical vessel wall fatty acids after normal and retarded fetal growth.

In a prospective observational study, the fatty acid content of human umbilical artery and vein wall phospholipids was determined in fetuses classified according to their change in abdominal circumference during the third trimester. Three groups were identified: appropriate for gestational age (AGA; 24 infants) and small for gestational age (SGA; 38 infants) with normal antenatal growth rate, and SGA with fetal growth retardation (22 infants). The venous linoleic acid (18:2 omega 6) content (expressed as a percentage of the total fatty acids identified) was greater in growth retarded SGA fetuses (3.5 (0.6)%) than in SGA fetuses with a normal growth rate (3.1 (0.5)%) and AGA fetuses (3.0 (0.5)%), whereas the venous contents of eicosatrienoic (20:3 omega 6) and docosahexaenoic acid (22:6 omega 3) were lower. In growth retarded SGA fetuses, the venous and arterial 20:3 omega 6 content correlated with the change in abdominal circumference. In SGA fetuses with a normal growth rate, lower contents of arterial 18:2 omega 6 and 22:6 omega 3 were associated with a smaller change in abdominal circumference and birth weight. Different metabolic derangements appear to underly normal and subnormal growth rate in SGA fetuses, suggesting that different strategies of dietary intervention may be required to aid fetal growth and reduce the sequelae of fetal growth retardation.

Abdomen↗
PubMed1994

Hormonal changes in elderly men with non-insulin-dependent diabetes mellitus and the hormonal relationships to abdominal adiposity.

To elucidate the hormonal changes in elderly men with non-insulin-dependent diabetes mellitus (NIDDM) and the hormonal relationship to abdominal adiposity, we measured serum insulin-like growth factor 1 (IGF-1), T3, T4, TSH, testosterone, LH, and FSH levels, body mass index (BMI), skinfold thickness and waist-to-hip circumference ratio (W/H) in 40 elderly men (aged over 60 years), 20 elderly men with NIDDM (aged over 60 years) and 30 men aged 21-40 years (controls). The results showed that elderly men with and without NIDDM had lower serum T3, testosterone and IGF-1 levels and higher serum LH and FSH levels compared with controls. Elderly men with NIDDM had even lower serum testosterone levels compared with elderly men without NIDDM. Elderly men had a higher W/H ratio compared with controls. Elderly men with NIDDM had a higher W/H ratio, BMI and skinfold thickness than elderly men without NIDDM. Age was positively correlated with the W/H ratio. Serum LH and FSH levels were positively correlated with the W/H ratio, and serum IGF-1, T3 and testosterone levels were negatively correlated with W/H ratio. Age, serum IGF-1, T3, T4, TSH, LH and FSH levels were not related to BMI or skinfold thickness. Only serum testosterone levels were negatively correlated with BMI or skinfold thickness. In conclusion, elderly men with NIDDM were associated with a marked decrease in serum testosterone levels and an increase of the W/H ratio compared to other groups in addition to the age-associated decrease of serum T3, IGF-1 and testosterone levels and increase of the W/H ratio and serum LH and FSH levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdomen↗
PubMed1994

Growth discordancy, birth weight, and neonatal adverse events in third trimester twin gestations.

In order to understand the effects of intrauterine growth discordancy (15% or more birth weight difference), birth weight, and gestational age on the neonatal adverse events (including 1- or 5-min Apgar scores < 7, neonatal death, ICU admission, respiratory distress, hypoglycemia, hypocalcemia, perinatal infection, blood transfusion, and hyperbilirubinemia) in third trimester twin gestations, 279 consecutive twin pairs delivered from January 1986 to December 1991 were studied. Univariate analyses showed discordant twins were smaller than concordant twins in gestational age by 1.4 weeks (35.74 and 37.14 weeks respectively). When birth weight was compared, that of smaller (one with lower birth weight in a pair) discordant twins (1,951 g) was significantly lower than that of smaller concordant twins (2,423 g), while larger (one with higher birth weight in a pair) discordant twins (2,556 g) and concordant twins (2,594 g) showed no significant difference. Univariate analysis indicated there was a tendency for adverse events to occur in discordant twins, especially in the smaller twin. Through logistic regression analysis, it was found that birth weight and gestational age, but not discordancy, are the predictors of the occurrence of adverse events. A smaller twin weighing no more than 2,000 g has a 10 times greater risk to develop an adverse event as compared to a twin with a birth weight over 2,000 g and a similar gestational age; while a twin with a gestational age of less than 34 weeks has a 5 times greater risk than one 34 weeks or over with a similar birth weight.

Apgar Score↗
PubMed1994

Effect of grinding and fluoride-gel exposure on strength of ion-exchanged porcelain.

Strengthening of dental porcelain through a diffusion heat treatment at 450 degrees C of a potassium-enriched, ion-exchange surface coating has been demonstrated in several recent studies. However, little attention has been focused on the potential strength reduction of these materials when the treated surfaces are ground or etched under clinically simulated conditions. The objective of this study was to test the hypothesis that partial removal of the surface layers of ion-exchanged porcelains by grinding or exposure to acidulated fluoride gel will significantly reduce their flexure strength. Nine groups of body porcelain disks were ion-exchanged at 450 degrees C for 30 min. One of these groups was subjected to ion exchange and no further surface treatment. Eight specimen groups were subjected to the following procedures after ion exchange: grinding to depths of 50 microns, 100 microns, 150 microns, 200 microns, and 250 microns, and exposure to acidulated fluoride for 30 min, 60 min, and 300 min. A tenth group (FC) was fired at 960 degrees C and fast-cooled in air, but the disks were not subjected to the ion-exchange treatment. Surface stress was calculated from measured values of cracks induced in the treated surfaces. Fluoride exposure for up to 60 min resulted in a significant decrease in surface compression (P < or = 0.05), although this treatment had no effect on strength. Grinding to a depth of from 100 microns to 250 microns caused a significant decrease in strength, while removal of a 50-microns layer caused no significant change (P > 0.05).

Acidulated Phosphate Fluoride↗
PubMed1994

Detection of penicillin G in milk using a conductimetric method.

A highly sensitive method was developed that used conductance measurement for the detection of penicillin G in milk. The method is based on the inhibition by the antibiotic on the growth of Bacillus stearothermophilus ATCC 10149. The conductance change in PM indicator agar containing the bacterial spores was continuously monitored at 55 degrees C by a microbiological analyzer, and the detection time was delayed when penicillin G was present in the samples. The detection limit of the method for penicillin G was .00016 IU/ml with a detection time of about 3.4 h, but only a narrow range (.00016 to .00062 IU/ml) of the antibiotic could be quantitatively analyzed. The conductimetric method is about 30 times more sensitive than several methods currently used. In addition, the conductance measurement is fully automatic, and multiple samples, 120 or 240, can be analyzed simultaneously.

Animals↗
PubMed1994

The role of maternal serum alpha-fetoprotein, human chorionic gonadotrophin and oestriol in the antenatal screening of Down's syndrome.

The use of maternal age alone to identify pregnant mothers at risk of a fetus with Down's syndrome has recently been supplemented by maternal serum screening using biochemical markers such as alpha-protein, human chorionic gonadotrophin and oestriol. These tests have been reported to increase the sensitivity of antenatal detection of such fetuses from 35% to 67% with a false positive rate of 5%. However, these maternal serum markers may be affected by maternal weight, the smoking history of mothers and diabetes mellitus. Furthermore, such sensitivities are achieved only when gestational age is assessed accurately by ultrasound. Many further studies need to be carried out before the introduction of maternal serum screening into routine obstetric practice in Singapore. These include studies on the incidence of Down's syndrome in the local population, studies on the distribution of these serum markers in the second trimester of pregnancy, sensitivities and positive predictive values of such a test in the local population as well as the socio-economic implications of implementing such a screening test in the local obstetric population.

Adult↗
PubMed1994

Ultrasound evaluation of thyroid abnormalities and volume in Chinese adults without palpable thyroid glands.

Typical examination of the thyroid gland involves palpating the patient. If goiter is found, thyroid ultrasonography and/or aspiration cytology is usually performed in addition to assay of thyroid hormones and antibodies. However, palpation may not be sensitive enough to detect thyroid lesions. The purpose of this study was to evaluate the prevalence of thyroid abnormalities detected by ultrasonography in Chinese adults without palpable thyroid glands admitted for health examination. Two hundred and seventy-seven patients (aged 17 to 79 years; mean, 52 years) admitted to National Taiwan University Hospital for health examinations were included in this study. The thyroid was first palpated by a thyroidologist. Goiter was detected in 77 out of 277 patients (27.8%). Two hundred patients who had no palpable goiter underwent thyroid ultrasonography. Thyroid abnormalities were detected in 37 out of 200 patients (18.5%). These included 18 cases of thyroid cyst, 13 cases of solid nodule, and six cases of multiple nodules with ill-defined margins. Patients with thyroid abnormalities were older than those without lesions [59.3 +/- 9.2 years (mean +/- SD) vs 50.1 +/- 12.8 years, p < 0.001]. In addition, we also calculated the thyroid volumes of 163 patients who had neither palpable goiter nor lesions detected by ultrasonography. The thyroid volumes were 7.7 +/- 3.3 mL and positively correlated to the body mass index (BMI, r = 0.17, p < 0.05) and body weight (r = 0.28, p < 0.005). Males (n = 115) had larger thyroid volume than females (n = 48) (8.3 +/- 3.3 vs 6.1 +/- 2.6 mL, p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Ultrasonography and needle aspiration cytology in the diagnosis and management of parathyroid lesions.

To elucidate the diagnostic value of fine needle aspiration (FNA) cytology of ultrasonically suspected parathyroid lesions, we reviewed a series of 17 cases seen over the past two years. Patients with biochemically proven primary or secondary hyperparathyroidism were examined by ultrasonography using a 7.5-MHz linear transducer. Ultrasound-guided FNA cytologic examinations with Riu's stain were performed on 13 patients who had questionable ultrasonographic patterns. The aspirates were considered adequate in nine out of 13 cases (69%). The cytologic patterns, characterized by tight cohesion of naked nuclei with indistinct cell border showing hypermonomorphism and overlapping of nuclei, were noted in adenomatous and hyperplastic lesions. There were several different findings noted in the case of parathyroid carcinoma, including loose cohesion of nuclei, larger nuclear size, and prominent anisokaryosis. One patient with secondary hyperparathyroidism who previously had a neck exploration, received an ultrasonically-guided percutaneous alcohol injection to the parathyroid lesion after cytologic verification. The result was remarkable both in volume reduction and in clinical improvement. The results suggest that ultrasound-guided FNA cytologic examination with Riu's stain is safe, simple and helpful in the localization of parathyroid lesions prior to surgery or percutaneous alcohol ablation therapy.

Adenoma↗
PubMed1994

Influence of smoking on Graves' disease with or without ophthalmopathy and nontoxic nodular goiter in Taiwan.

The effect of smoking habits on Graves' disease with or without ophthalmopathy and nontoxic nodular goiter has been discussed for more than 10 years in Western countries, but there are no published reports from Oriental countries, where the prevalence of cigarette smoking among women is lower than in Western women. The purpose of this study was to determine the relationship between smoking and Graves' ophthalmopathy, Graves' disease without ophthalmopathy, and nontoxic nodular goiter in Taiwan. The study included 349 patients with thyroid disease from endocrinologic clinics, including 116 patients with Graves' ophthalmopathy (92 women, 24 men), 108 patients with Graves' disease but without ophthalmopathy (96 women, 12 men), and 125 patients with nontoxic nodular goiter (114 women, 11 men). Information on smoking habits at the time of onset of the disease was obtained by a self-administered structured questionnaire. Since women generally smoke less than men, female and male smoking habits were compared separately with those of controls matched with patients on the basis of age. There was a significantly higher prevalence of cigarette smoking in women with Graves' ophthalmopathy and nontoxic nodular goiter than for healthy female controls, showing an odds ratio of 8.15 and 6.48, respectively, despite a lower prevalence of cigarette smoking in Taiwan (7.6% in women with Graves' ophthalmopathy, 6.1% in women with nontoxic nodular goiter) than in the West (64.2% in women with Graves' ophthalmopathy, 30% in women with nontoxic nodular goiter). Men in these three disease groups and women with Graves' disease without ophthalmopathy showed no significant association with cigarette smoking.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Treatment of malignant germ cell tumors of the ovary.

Thirty-five patients with ovarian germ cell malignancies presenting from 1982 to 1992 were studied. The pathologic diagnoses were immature teratoma in 11 patients, endodermal sinus tumor in eight, dysgerminoma in 12, and mixed germ cell tumor in four. The median age at presentation was 20 years. Postoperative multiple-agent chemotherapy was given to 28 patients. Five out of 35 (14%) patients died of malignancy, three with endodermal sinus tumors with stage Ia, Ic, and IIIc, respectively, one with stage IIIc dysgerminoma, and one with stage IIIc mixed germ cell tumor. The other 30 patients were alive without evidence of disease from 14 to 124 months, with a median follow-up of 52 months. All eleven patients with immature teratoma were alive with no evidence of disease at 20 to 104 months of follow-up. Four patients with stage I, grade 1 immature teratoma were successfully treated with surgery alone. The other seven patients were treated with adjuvant chemotherapy and were disease-free. One patient with stage IIIc dysgerminoma was treated with surgery and radiotherapy but died of disease. The other eleven patients were safely treated with surgery and adjuvant chemotherapy with vincristine, actinomycin-D and cyclophosphamide (VAC) or platinum-based chemotherapy. For the more virulent tumors such as endodermal sinus tumor and mixed germ cell tumor, platinum-based chemotherapy should be used exclusively in view of the high failure rate of the VAC regimen. Preservation of fertility for young patients with malignant ovarian germ cell tumors is possible in the early stages of disease and in selected cases of advanced disease.

Adolescent↗