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T C Chang

Publications and source records attributed to T C Chang.

At least 19 recordsLinked to original sources
PubMed1992

Human placental alkaline phosphatase. An improved purification procedure and kinetic studies.

An improved method for the purification of human placental alkaline phosphatase is described. The partially purified enzyme from Sigma was further purified by successive Concanavalin A-Sepharose and Q-Sepharose chromatography. The whole procedure may be completed in one working day. Highly purified enzyme was obtained with a 39% yield. The intrinsic fluorescence of the enzyme decreased at elevated temperature. The conformation of the enzyme molecule was studied by the fluorescence quenching technique. Upward Stern-Volmer plots were obtained for the quenching data which suggested that, in addition to collisional quenching, static quenching was involved in the quenching mechanism. The dynamic and static quenching constants were found to be 0.7 +/- 0.16 M-1 and 0.44 +/- 0.1 M-1, respectively, using acrylamide as the quenching agent. The corresponding values were 0.43 +/- 0.23 M-1 and 0.84 +/- 0.18 M-1, respectively, with KI as the quenching agent. Mg2+ and PO4(3-) induced protein conformational changes which altered both the dynamic and static quenching constants. Mg2+ was found to be a non-essential activator for the placental alkaline-phosphatase-catalyzed hydrolysis of 4-nitrophenyl phosphate. At pH 9.8, Mg2+ increased Vmax by 1.2-fold without affecting the Kd of the substrate. The tetranitromethane-modified enzyme showed slower migration toward the anode on electrophoresis and increased Kd for Mg2+.

Alkaline Phosphatase↗
PubMed1992

Protein classification artificial neural system.

A neural network classification method is developed as an alternative approach to the large database search/organization problem. The system, termed Protein Classification Artificial Neural System (ProCANS), has been implemented on a Cray supercomputer for rapid superfamily classification of unknown proteins based on the information content of the neural interconnections. The system employs an n-gram hashing function that is similar to the k-tuple method for sequence encoding. A collection of modular back-propagation networks is used to store the large amount of sequence patterns. The system has been trained and tested with the first 2,148 of the 8,309 entries of the annotated Protein Identification Resource protein sequence database (release 29). The entries included the electron transfer proteins and the six enzyme groups (oxidoreductases, transferases, hydrolases, lyases, isomerases, and ligases), with a total of 620 superfamilies. After a total training time of seven Cray central processing unit (CPU) hours, the system has reached a predictive accuracy of 90%. The classification is fast (i.e., 0.1 Cray CPU second per sequence), as it only involves a forward-feeding through the networks. The classification time on a full-scale system embedded with all known superfamilies is estimated to be within 1 CPU second. Although the training time will grow linearly with the number of entries, the classification time is expected to remain low even if there is a 10-100-fold increase of sequence entries. The neural database, which consists of a set of weight matrices of the networks, together with the ProCANS software, can be ported to other computers and made available to the genome community. The rapid and accurate superfamily classification would be valuable to the organization of protein sequence databases and to the gene recognition in large sequencing projects.

Computers, Mainframe↗
PubMed1992

Neoadjuvant chemotherapy with cisplatin, vincristine, and bleomycin and radical surgery in early-stage bulky cervical carcinoma.

Neoadjuvant chemotherapy consisting of 2-3 courses of cisplatin, vincristine, and bleomycin was used in the primary treatment of 36 consecutive patients with locally advanced early-stage cervical carcinoma [International Federation of Gynecology and Obstetrics (FIGO) stages Ib or IIa; tumor size, greater than or equal to 4 cm]. The effectiveness of the preoperative chemotherapy was evaluated in the surgical specimens. Among the 33 evaluable patients, the overall clinical response rate was 84.8%, which included a complete response in 8 patients (24.2%) and a partial response in 20 subjects (60.6%). No residual tumor was found in the surgical specimens obtained from 2 complete responders. This therapy induced varying degrees of tumor shrinkage and rendered radical surgery feasible in all evaluable cases despite the initial bulky size of the lesions. No significant difference was observed in the response rate according to age and disease stage. Lymph-node metastases were found after chemotherapy in 18.2% (6/33) of the patients. Grade II and III hematological toxicities occurred in 23.3% of the 90 chemotherapy cycles completed. Nausea and vomiting occurred to a mild to moderate degree in 75 (83.3%) cycles. These preliminary results suggest that the administration of induction chemotherapy involving two to three courses of cisplatin, vincristine, and bleomycin prior to surgery is effective in reducing the tumor volume and in providing better circumstances for surgical removal of the early yet bulky cervical tumors and results in tolerable toxicity. This protocol is now undergoing prospective randomized trials to test its impact on long-term survival.

Adult↗
PubMed1992

Identification of autoantigen recognized by autoimmune ophthalmopathy sera with immunoblotting correlated with orbital computed tomography.

We have demonstrated that there is an antibody related to extraocular muscle enlargement in autoimmune ophthalmopathy (Graves' ophthalmopathy, thyroid-associated correlated with orbital computed tomography (CT). This study was designed to identify the autoantigen and to determine whether there are common antigens among the extraocular muscle, the lacrimal gland, and the thyroid. We prepared a 100,000g sediment fraction of porcine extraocular muscle, lacrimal gland, thyroid, and human thyroid, followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting with sera from patients with Graves' disease, with or without ophthalmopathy, classified by symptoms and signs combined with orbital CT and normal controls. The results showed there was an approximately 55-kDa protein band which was recognized by the sera in 32.1% (9/28) of patients with autoimmune ophthalmopathy and in 47.3% (9/19) of patients with extraocular muscle enlargement demonstrated by orbital CT. It was significantly higher than the positive rates in patients without autoimmune ophthalmopathy and normal controls (15.8 and 11.1%, respectively, P < 0.025). However, there was no common antigen among the extraocular muscles, the lacrimal gland, and the thyroid. To further confirm this eye muscle-specific antigen, the approximately 55-kDa protein band was cut and solubilized from the nitrocellulose paper after SDS-PAGE, and electrophoretically transferred and used as an antigen in enzyme-linked immunosorbent assay. The absorbance was significantly higher in patients with autoimmune ophthalmopathy than patients without ophthalmopathy (P < 0.005), and normal controls (P < 0.01). Our findings suggest that an approximately 55-kDa protein may be a possible antigen in the eye muscle related to autoimmune ophthalmopathy.

Animals↗
PubMed1992

The role of estrogen response elements in expression of the Xenopus laevis vitellogenin B1 gene.

We have used site-directed mutagenesis and a homologous transient transfection system to investigate the role of the two imperfect estrogen response elements (EREs) located at -302/-334 in the 5'-flanking region of the estrogen-regulated Xenopus laevis vitellogenin B1 gene. Deletion of either ERE effectively abolishes estrogen-dependent transcription of the vitellogenin promoter. Neither replacement of the two imperfect EREs with a single consensus ERE at -334, nor insertion of one or two consensus EREs at -359, restores full estrogen responsiveness to the mutant promoter. In competition gel mobility shift assays using the DNA binding domain of the Xenopus estrogen receptor, the consensus ERE was a severalfold more effective competitor than the two imperfect B1 EREs. These data suggest that flanking DNA sequences may exert a significant effect on the activity of EREs as hormone-dependent transcription activators. When the imperfect EREs at -302/-334 were present, an additional consensus ERE at -359 exhibited synergistic activation of transcription. However, two consensus EREs located close to the TATA box showed additive, not synergistic, activation of transcription. In contrast, synergistic activation of transcription was observed in synthetic promoters containing two EREs and either the vitellogenin activator element or the NF1 or AP1 upstream activator elements.

Animals↗
PubMed1992

Choriocarcinoma of the cervix.

The incidence of primary cervical choriocarcinoma is extremely low, with only approximately 60 cases reported. We present a case of primary cervical choriocarcinoma, which was originally mis-diagnosed as a cervical pregnancy. After failure of conservative treatment with methotrexate, the patient underwent a hysterectomy, followed by chemotherapy with actinomycin-D. After twenty months of follow-up, the patient is in good condition and her serum beta-hCG levels are normal.

Adult↗
PubMed1992

Effect of estrogen on the serum level of thyroglobulin.

Thyroglobulin has been widely accepted as a useful parameter for monitoring the recurrence of differentiated thyroid carcinoma. In thyroid cell cultures, it has been reported that estrogen may stimulate the tgb gene which controls synthesis of thyroglobulin by the thyroid follicular cell. Since the serum estrogen levels of women fluctuate during the menstrual cycle, pregnancy and menopause, thyroglobulin may be unreliable in the follow-up of recurrence of differentiated thyroid carcinoma in females if it can be affected by estrogen in vivo. In order to clarify the effect of estrogen on thyroglobulin, the sera of 16 men, 42 women and 20 children were collected and divided into seven groups. Their serum estradiol and thyroglobulin levels were 17.7 +/- 1.8 pg/mL (mean +/- SEM) and 17.1 +/- 1.6 ng/mL, respectively in 20 children, 26.7 +/- 4.1 pg/mL and 12.9 +/- 1.2 ng/mL, respectively in 16 males, 151.6 +/- 20.4 pg/mL and 13.7 +/- 4.2 ng/mL, respectively in five females on the 10th to 14th days of the menstrual cycle, 16.7 +/- 1.8 pg/mL and 15.2 +/- 2.1 ng/mL, respectively in 12 postmenopausal females, 530.0 +/- 131.0 pg/mL and 14.2 +/- 1.8 ng/mL, respectively in eight pregnant women in the first trimester, 3613.9 +/- 1014.2 pg/mL and 12.0 +/- 1.6 ng/mL, respectively in seven pregnant women in the second trimester and 9246.0 +/- 694.5 pg/mL and 16.4 +/- 2.0 ng/mL, respectively in 10 pregnant women in the third trimester. The serum estradiol levels were significantly different (p less than 0.005) among these seven groups, but the serum thyroglobulin levels were not (p = 0.25). Therefore, serum thyroglobulin levels are not affected by estrogen.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Clinical experience of octreotide in the treatment of acromegaly.

To evaluate the efficacy and safety of octreotide (a somatostatin analogue) in the treatment of acromegaly, 10 patients were injected subcutaneously with octreotide, 50 micrograms, thrice daily before each meal for two days, followed by 100 micrograms thrice daily for six months. One case dropped out at the initial stage because of diarrhea, and another quit due to a lack of improvement in headaches after treatment for three months. Eight patients completed the study. The results showed that the circumference of the fourth finger and hand volume significantly decreased after treatment. Laboratory data demonstrated that serum growth hormone (GH) and somatomedin-C levels also decreased significantly. However, in six patients without a history of trans-sphenoidal adenomectomy, the serum GH and somatomedin-C levels returned to normal in only one case who had a serum GH level < 20 mU/L before treatment. In the oral glucose tolerance test, paradoxic elevation of GH subsided after treatment. In the TRH test, paradoxic elevation of GH improved after treatment. In the bromocriptine test, octreotide had a synergistic effect on the suppression of GH. All cases had the side effect of injection pain, especially at the initial stage. An increase in intestinal peristalsis and bowel movement occurred in the first week, but symptoms later subsided. Two out of these eight patients had gallbladder sludge after six months of treatment. In conclusion, octreotide is effective in the treatment of acromegaly; however, it is better used in patients who have serum GH levels < 20 mU/L, or after a trans-sphenoidal adenomectomy, and may be combined with bromocriptine to treat the patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Acromegaly↗
PubMed1992

Cardiac tamponade resulting from recurrent small-cell carcinoma of the uterine cervix temporarily responding to CE/CAV chemotherapy: report of a case.

A case of recurrent small-cell carcinoma of the uterine cervix, initially presenting with cardiac tamponade, is reported. After pericardiotomy, the patient was treated with an alternating combination of chemotherapy, which included cisplatin plus etoposide (CE) and cyclophosphamide, adriamycin plus vincristine (CAV). A partial response, with relief of a cough and diminishing metastatic pulmonary lesions, was noted from serial chest roentgenographs after the initial three cycles of chemotherapy. The patient did not receive any further treatment and the recurrent cough and dyspnea were noted two months later. In spite of the same chemotherapeutic regimen and chest radiotherapy, the patient died nine months after the initial diagnosis of metastasis.

Adult↗
PubMed1992

Prevalence of goiters in school children residing in villages where underground water is used.

A representative of Fuder village in Taichung County complained that many residents had a goiter problem, which he felt might be related to pollution from the nearby Youshi industrial area. The purpose of this study was to determine whether school children in the Fuder area have a high prevalence of goiters. We chose children of the Schichi elementary school in the Fuder area as the study population, and children of the Goumei elementary school, far from the Youshi industrial area, as controls. Both groups were from a similar geographic location (near the sea), had similar socioeconomic status, and both drank underground water. Thyroid enlargement was examined by palpation as recommended by the World Health Organization. Thyroid antibodies and hormones were determined in school children with a goiter and age-sex-matched normal control children using the particle agglutination method and radioimmunoassay, respectively. In total, 1,692 school children were examined, including 875 males and 817 females. Of these, 126 school children (7.4%) had a goiter of Grade I or above. The prevalence of goiters in Shichi and Goumei were 8.8% (59/671) and 6.6% (67/1,021), respectively. There was no significant difference between these two areas. We compared the prevalence of goiters in these two schools where underground water is drunk with another previous study in Peimen and Putai where tap water is used. There was a statistically significant difference (7.4% vs 2.6%, p < 0.0001). This suggests that the higher prevalence rate of goiters in Shichi and Goumei is related to the drinking of underground water. We recommend that the use of tap water and continued salt iodization is the way to prevent endemic goiter in these areas. A further comprehensive study is needed to determine the nature of the goitrogen in the underground drinking water of the Fuder area.

Child↗
PubMed1992

Surgical management of Graves' ophthalmopathy: stage I, inferomedial orbital decompression.

Inferomedial orbital decompression was done on 26 eyes with dysthyroid optic neuropathy (DON), seven eyes with corneal exposure which had not responded to topical lubricants, and six with disfiguring exophthalmos. Twenty-one of the 26 DON eyes (80.7%) had visual acuity improvement equal to or greater than two lines by the Snellen chart, and there was only one in all 39 eyes that dropped more than two lines. The average retinal sensitivity improvement was of borderline significance (4.25 +/- 5.73 dB), but for those 13 severely affected eyes (preoperative sensitivity loss > or = 10 dB), 11 (84.6%) of them showed significant improvement. There were 16 bilateral and seven unilateral cases. Out of all 39 eyes, the average retroplacement effect was 4.6 +/- 2.3 mm, and none of them had postoperative asymmetry greater than 2 mm by Hertel's exophthalmometry. Although the palpebral fissure height tends to remain the same after surgery, upper lid retraction is likely to be worse. The most frequent sequela was diplopia, which tended to occur in more severely myopathic eyes regardless of the surgical approach used. Although a staged approach is mandatory in surgical treatment of this disorder, individualization of surgical goals and intraoperative titration of the retroplacement effect are of equal importance for optimal results.

Adult↗
PubMed1992

Prediction of the small for gestational age infant: which ultrasonic measurement is best?

OBJECTIVE: To determine the most appropriate ultrasonic measurement for the prediction of a small for gestational age (SGA) infant. DATA SOURCES: A literature search of all English language journals over the last 15 years was undertaken. One hundred seventeen articles on the use of morphometric and Doppler ultrasonic measurements in the diagnosis of SGA were reviewed. METHODS OF STUDY SELECTION: Studies were included if antenatal and postnatal criteria for diagnosis were clearly defined and data for SGA and normal fetuses were reported, allowing the construction of a 2 x 2 table. DATA EXTRACTION AND SYNTHESIS: Studies with the same criteria were grouped according to whether the population was high or low risk. The sensitivity, odds ratio (OR), and false-positive rate were calculated for each study; summary statistics were then calculated for each ultrasonic measurement provided the individual sensitivities, ORs, and false-positive rates were not significantly different (P > .01). CONCLUSIONS: In high-risk subjects, abdominal circumference below the tenth percentile had the highest common sensitivity, and estimated fetal weight below the tenth percentile had the highest common OR. In studies in which morphometric and Doppler ultrasonic measurements were compared in the same subjects, the Doppler ORs tended to be lower than the ORs for morphometric measurements. In low-risk subjects, much lower ORs were found for all ultrasonic measurements. The heterogeneous nature of the studies reviewed may have contributed to the different results within each group.

False Positive Reactions↗
PubMed1991

Blood content in guinea-pig tissues: correction for the study of drug tissue distribution.

The blood content in different organs or tissues of guinea-pigs was determined by means of [125I]bovine serum albumin. The blood distribution expressed as percentage of total body blood for various organs or tissues ranged from 0.35 (adipose) to 17.5 (muscle)%. The blood content in tissue preparations expressed as the blood background correction factor, F (ml blood/g wet tissue) depended on the extent of bleeding during experiment; that factor can cause a considerable difference in the results of a tissue distribution study of a drug. Blood content was high in the lung (0.36 ml/g), heart, liver, kidney and spleen, but low in adipose and brain tissues (0.021 ml/g). The distribution of valproic acid in various tissues of guinea-pigs after intravenous injection was determined from the homogenates of isolated organs. The results showed that blood contamination can greatly alter the data of tissue distribution of a drug to as much as 25%. This study proposed a maximum (non-bled) and a minimum (extreme-bled) blood background correction factor for respective tissues of guinea-pigs, as well as equations for correcting the blood contamination in tissue during the drug distribution study. The results suggest that to obtain an exact analysis of drug concentrations in specific tissues, a correction for the blood of that specific tissue is necessary.

Animals↗
PubMed1991

Higher prevalence of goiter in endemic area of blackfoot disease of Taiwan.

Blackfoot disease is an endemic peripheral vascular disorder which is confined to a limited land area on the southwest coast of Taiwan. It has long been related to the consumption of high levels of arsenic found in the artesian well water. Humic substances have also been extracted from the well water and have been reported as a possible source of environmental goitrogen. The purpose of this study was to examine whether the prevalence of goiter is increased in the blackfoot disease-endemic area. This study covered all the children in the elementary schools of Putai and Peimen. They were divided into two groups according to the location of schools in the endemic area or non-endemic area of blackfoot disease. Thyroid enlargement was examined by palpation as recommended by the World Health Organization. Thyroid antibodies and hormones were determined in school children with a goiter and age-sex-matched normal control children using particle agglutination methods and radioimmunoassays, respectively. Aspiration cytology was done in cases with a nodular goiter. In total 4,567 school children were examined, including 2,306 males and 2,261 females. One hundred and twenty school children (2.63%) had a goiter of grade I or above. The prevalence of goiters in school children from the endemic area was higher than that from the non-endemic area (3.44 vs 2.08%, p less than 0.01). The prevalence of goiters in females from the endemic area was higher than that from the non-endemic area (4.65 vs 2.69%, p less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Biomarkers↗
PubMed1991

Coefficient of variation of nuclear diameters as a prognostic factor in papillary thyroid carcinoma.

To determine whether the coefficient of variation (CV) of nuclear diameters can be used as a prognostic factor in papillary thyroid carcinoma, we reviewed fine needle aspiration smears with Riu's stain from 55 operated-on and pathologically verified cases with a median follow-up of 6.5 years. For each case we measured the nuclear diameters of 100 cancer cells by ocular micrometry and calculated the CV of the nuclear diameters. Then we correlated the CV with the clinical stage, recurrence and death. There was a positive correlation between the CV of the nuclear diameters and the clinical stage (r = .59, P less than .0001). Recurrent cases (n = 10) had a higher CV than did those without recurrence (n = 45) (18.04 +/- 4.1% [mean +/- SD] versus 13.2 +/- 2.7%, P less than .0005). All recurrent cases had a CV greater than 13%. The cases in which death occurred (n = 5) had a higher CV than did those with survival (n = 50) (20.1 +/- 4.9% versus 13.5 +/- 2.7%, P less than .0005). All cases in which death occurred had a CV greater than 15%. The extent of variation of nuclear diameters was one of the factors influencing prognosis in papillary thyroid carcinoma. It offers a prognostic adjunct to standard clinical and histologic analysis.

Adult↗