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Biomedical subjects

T C Chang

Publications and source records attributed to T C Chang.

At least 181 records · Page 10Linked to original sources
PubMed1990

Pregnancy induces the presence of a thyroid-stimulating antibody in a thyrotropin-binding inhibitory immunoglobulin positive, hypothyroid woman with transient thyrotoxicosis in offspring.

A 27-year-old woman had a goiter and transient hyperthyroidism when she was 18 years old. Symptoms subsided after treatment with medication (without use of radioactive iodine) for one month. She delivered a child without complications at 23 years of age. Hypothyroidism developed when she was 25 years old. Under the impression of autoimmune thyroiditis with hypothyroidism, she was treated with levothyroxine 150 micrograms/day. She became pregnant again one year later. Her thyrotropin-binding inhibitory immunoglobulin (TBII) was very high before and during pregnancy, and after delivery. Thyroid-stimulating antibody (TSAb) was not detectable during the 2nd trimester, but elevated in association with a decrease in dosage of levothyroxine during the 3rd trimester. She delivered a male baby at full-term. The newborn's TBII was high at 4 days old and it gradually developed into hyperthyroidism with symptoms of irritability, poor weight gain, tachycardia and jaundice. Hyperthyroidism subsided after temporary treatment with methimazole and propranolol. The medication was discontinued at the age of 82 days. Follow-up thyroid function was normal at the age of three and a half months. In the mother, TSAb gradually decreased, although TBII was still very high. The dosage of levothyroxine was again increased. This study demonstrates that pregnancy may alter the ratio of TBII and TSAb, and modify the functional state of the thyroid of the mother. Therefore, in patients with autoimmune thyroiditis during pregnancy, serial follow-up of thyroid function and TBII (and TSAb, if possible) may help the doctor to properly adjust the treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Correlation between sonography and pathology in thyroid diseases.

Ultrasonography was performed on the thyroid glands of 47 patients with various thyroid diseases, in a fresh state, immediately following operation. The thyroid glands were then sectioned along the plane of the most significant sonographic changes. The pathologic changes of the sectioned plane were observed and compared with the sonographic changes. In nodular goiter, the sonographic changes were usually heterogeneous. The margin was either well-defined or ill-defined, and cystic changes might play a minor or major part in the thyroid nodules. In follicular adenoma, the changes were isoechoic in adenoma with embryonal type follicles and hyperechoic in adenoma with colloid type follicles. In adenoma of the oxyphilic cells, the echogenicity was somewhat greater in the hemorrhagic part compared to the area with oncocytic change only. In papillary carcinoma, the lesions usually manifested as well-limited, heterogeneous, hypoechoic nodules. Cystic degenerations were frequently noted. There were discrete particles corresponding to microcalcification in 4 out of 6 cases. In follicular carcinoma, the sonographic changes also showed well-limited nodules. However, the echogenicity was not decreased as much as in papillary carcinoma, and it could be either homogeneous and isoechoic, or hypoechoic. Relatively large particles with an acoustic sign, which corresponded to calcification, were noted in 2 out of 4 cases. In medullary carcinoma, the lesion was well-limited and hypoechoic. The particles present in sonography corresponded to calcification in the amyloid. In Graves' disease, the main sonographic change was a diffusely homogeneous, isoechoic or hypoechoic lesion. Cystic change was rarely present. Dispersed particles were rarely present and corresponded to fibrosis in the thyroid tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Goiter, Nodular↗
PubMed1990

Sonographic presentation in autoimmune thyroiditis.

We used real-time ultrasonography to examine 60 patients with autoimmune thyroiditis, then correlated the ultrasonic pictures with thyroid function, thyroid autoantibodies and fine needle aspiration cytology. In these 60 patients, 45 (75%) showed diffuse goiter, 6 (10%) showed multinodular goiter, and 9 (15%) had a solitary thyroid nodule sonographically. One of the 9 patients with a solitary nodule was a case of autoimmune thyroiditis combined with papillary carcinoma. The echogenicity of the thyroid was more than, the same as, or less than that of the adjacent muscles in 17, 22, and 21 patients, respectively. The groups were classified as hyperechoic, isoechoic, and hypoechoic, respectively. The mean serum T4 level was significantly lower in the hypoechoic group than in the hyperechoic or isoechoic groups (p less than 0.01 and p less than 0.05, respectively), and the incidence of hypothyroidism was significantly higher in the hypoechoic group than in the hyperechoic or isoechoic groups (p less than 0.001 and p less than 0.005, respectively). In addition, high titers of the antithyroid microsomal antibody (greater than or equal to 1280) were present more frequently in the hypoechoic group than in the hyperechoic or isoechoic groups (p less than 0.01 and p less than 0.05, respectively). There was no significant correlation between the cytomorphology and echogenicity of the thyroid in these cases. We conclude that sonography has two major uses in evaluating autoimmune thyroiditis: First, it is useful in excluding the coexistence of thyroid nodules; and second, marked hypoechogenicity of the thyroid implies an active cytotoxic autoimmune process and possibly a hypothyroid state.

Humans↗
PubMed1990

Intractable diabetic ketoacidosis due to insulin antibody--response to steroid therapy.

To examine the effect of steroid therapy on insulin antibody titer in insulin-dependent diabetes mellitus, we studied a 58 year-old gentleman with recurrent diabetic ketoacidosis. No any overt precipitating factors could be accounted for, except limited pancreatic beta cell reserve and high titers of anti insulin antibodies. Despite the persistence of high titers of plasma antiinsulin antibodies, the clinical manifestations of diabetic ketoacidosis improved greatly by the administration of steroid. Nevertheless, the patient still showed the great excursion of plasma glucose concentration.

Diabetes Mellitus, Type 1↗
PubMed1990

An in vitro approach to the kinetics of insulin antibodies in diabetic patients.

The purpose of this study is to evaluate the binding behavior of plasma insulin antibodies (Iab) in diabetic patients, by the following parameters: Incubation time, temperature, buffer pH, and Iab titer. We investigated the plasma insulin binding patterns of 12 insulin-treated diabetic patients, and they were separated as higher titer group (Iab = 51.9 +/- 7.28, n = 6) and lower titer group (Iab = 14.88 +/- 4.75, n = 6). The procedure was: (1) plasma samples were deinsulinized by 0.12N HCL, dextran coated charcoal suspension and 0.12N NaOH. (2) I-125 monoiodoinsulin was used to prevent artifacts resulting from variability in ligand binding due to excessive iodination, (3) separation of free and bound insulin was accomplished by rapid precipitation of hormone-antibody complex with polyethylene glycol, and (4) decanting the supernatants and counting the pellets in the automatic gamma counter. The data were obtained as the condition of incubation time, temperature, buffer pH, and Iab titer. The results obtained by the Scatchard analysis indicated that high temperature (39 degrees C vs 37 degrees C) in vitro would increase the free insulin levels and decrease the low affinity binding capacity (Q2-Q1) of Iab in patients with high titer of Iab (greater than 40%), whereas this phenomenon is not observed in patients with low affinity binding sites of Iab in patients with low titers of insulin antibodies (less than 20%).

Antigen-Antibody Reactions↗
PubMed1990

Comparison of insulin secretion and insulin sensitivity between normal and impaired glucose tolerance subjects with normal fasting plasma glucose.

To examine glucose-stimulated insulin secretion and insulin sensitivity in the normal subjects and patients with impaired glucose tolerance, we performed the oral glucose tolerance test (OGTT) and modified insulin suppression test in 34 non-obese subjects. The plasma glucose and insulin concentrations were measured during fasting and every 30 min up to 120 min following 75 g of oral glucose loading. Ten subjects were classified as impaired glucose tolerance (IGT), and 24 subjects were as having normal glucose tolerance. In addition, the insulin-stimulated glucose uptake was estimated in all subjects by measuring the final 30 min steady-state plasma glucose (SSPG) of a continuous infusion of somatostatin, insulin and glucose for 4 hours (modified insulin suppression test). The mean plasma glucose concentrations of fasting and 60, 90, 120 min during OGTT study were significantly higher in the IGT subjects than in the normals. In addition, the mean incremental glucose areas under the curve during OGTT study were also greater in the IGT subjects than in the normals. The mean serum insulin concentrations were significantly higher at 90 and 120 minutes in the IGT patients than in the normals. During the modified insulin suppression test, the mean SSPG concentrations were significantly higher in the IGT patients than in the normals under the similar steady-state plasma insulin in both groups. There was a good correlation between the incremental insulin areas under the curve (OGTT) and the SSPG in the normal subjects (p less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

The action of gliclazide on insulin secretion and insulin sensitivity in non-obese non-insulin dependent diabetic patients.

We evaluated the effects of gliclazide on the secretion and action of insulin in 18 non-obese (BMI 24.09 +/- 0.47 Kg/m2, range 20.89-27.52 Kg/m2) non-insulin dependent diabetic patients (mean age 56.9 +/- 1.8 years, range 39-67 years) by the oral glucose tolerance test (OGTT) and insulin suppression test (IST). Most of them were diagnosed recently and thus untreated previously. All subjects were treated with gliclazide or placebo for 3 months in a double blind cross-over design. After gliclazide therapy, fasting and 2 hour post-OGTT plasma glucose significantly decreased (136 vs. 185 mg/dl, P less than 0.005 291 vs. 358 mg/dl, P less than 0.005), 2 hours post-OGTT plasma insulin was significantly increased (79 vs. 59 uU/ml, P less than 0.05) while fasting plasma insulin remained unchanged (21 vs. 19 uU/ml, P greater than 0.1). HbAlc decreased significantly with gliclazide therapy (6.6 vs. 7.6%, P less than 0.005). In addition, oral glucose tolerance, as measured by the mean incremental areas under the plasma glucose curve, were improved significantly (1430.6 +/- 682.4 vs. 16192.5 +/- 608.5 mg.min/dl, P less than 0.005). The mean incremental areas under the plasma insulin curve during OGTT also increased (4482.0 +/- 637.1 vs. 3167.5 +/- 511.9 uU.min/ml, P less than 0.05) after gliclazide therapy. Mean steady state plasma glucose levels (SSPG) showed no remarkable difference during drug and placebo administration (188 vs. 190 mg/dl). Throughout the trial there was no significant change of body weight, nor any side effect as judged from blood counts, urinalysis, and the results of SMA-23 and EKG.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Lipid cell tumor of the ovary associated with endometrial adenocarcinoma--a case report.

Presented here is a case of a 54-year-old woman with a lipid cell tumor of the ovary associated with endometrial adenocarcinoma. Lipid cell tumor of the ovary is a rare tumor. From the previous literature, there are only four cases reported to be associated with endometrial adenocarcinoma. The history and the pathological findings will be presented along with the review of the literature.

Adenocarcinoma↗
PubMed1989

A highly sensitive, mixed-phase assay for chloramphenicol acetyltransferase activity in transfected cells.

We describe a simple, rapid yet extremely sensitive assay for chloramphenicol acetyltransferase (CAT) activity in extracts from transfected eukaryotic cells. Using our modified reaction conditions and the mixed-phase assay, less than 0.000010 unit of CAT activity in transfected cells can be reliably detected. The mixed-phase assay is based on the inability of the polar [3H]-acetyl-Coenzyme A (CoA) substrate to partition out of a urea containing aqueous phase into the nonpolar scintillation fluor, while the [3H]chloramphenicol reaction products partition into the toluene scintillation fluor and are quantitated by scintillation counting. The increased sensitivity of this assay is due to the optimization of the acetyl-CoA concentration, to a urea-containing aqueous phase which lowers the assay background, and to the use of extract blanks. The mixed-phase assay is simpler, is quantitative, uses less costly substrates, and is far more sensitive than the most widely used CAT assays, which require solvent extraction followed by thin-layer chromatography to separate the unreacted substrate from product.

Animals↗
PubMed1989

Thyroxine may decrease serum thyroxine-binding globulin levels.

The purpose of this study was to elucidate the influence of thyroxine on the serum thyroxine-binding globulin (TBG) levels. Serum TBG levels were determined in 100 normal people, 100 cases of simple goiter, 50 cases of nodular goiter, 50 cases of Graves' disease and 70 cases of autoimmune thyroiditis (35 cases in the euthyroid state, and 35 cases in the hypothyroid state). The serum TBG levels were 14.3 +/- 0.3 micrograms/ml (mean +/- SE) in the normal control, 14.1 +/- 0.4 micrograms/ml in simple goiters, 14.9 +/- 0.5 micrograms/ml in nodular goiters, 13.0 +/- 0.5 micrograms/ml in Graves' disease, 15.0 +/- 0.6 micrograms/ml in euthyroid autoimmune thyroiditis and 17.4 +/- 0.8 micrograms/ml in hypothyroid autoimmune thyroiditis. The serum TBG levels were significantly decreased in Graves' disease (p less than 0.05) and significantly increased in hypothyroid autoimmune thyroiditis (p less than or equal to 0.01) as compared with the control. Serum TBG levels were determined after treatment by antithyroid drugs in 25 cases of Graves' disease, by thyroxine replacement therapy in 15 cases of hypothyroid autoimmune thyroiditis and by thyroxine suppression therapy in 25 cases of nodular goiter. Serum TBG levels increased significantly after treatment with antithyroid drugs (p less than 0.005) in Graves' disease. Serum TBG levels decreased significantly both after treatment with thyroxine (p less than 0.01) in hypothyroid autoimmune thyroiditis and after treatment with thyroxine (p less than 0.005) in nodular goiter. This evidence supports the conclusion that T4 may decrease serum concentrations of TBG.

Animals↗
PubMed1989

Influence of lithium carbonate on the thyrotropin receptor in vitro.

Thyroid tissues excised from 5 patients with Graves' disease were used to study the influence of lithium carbonate on the thyrotropin (TSH) receptor in vitro by cAMP generation assay and TSH binding to its receptor. Lithium carbonate was able to decrease the cAMP production of the crude thyroid plasma membranes stimulated by TSH at concentrations of 6mM and higher. However, lithium carbonate had no effect on 5'-guanylylimidodiphosphate-induced cAMP production in thyroid plasma membranes up to concentrations of 10mM. Lithium carbonate was able to decrease the binding of 125I-TSH to crude thyroid plasma membranes at concentrations of 6mM and higher. It decreased the binding of 125I-TSH to solubilized TSH receptor at concentrations of 6mM and higher. These findings suggest that lithium carbonate can influence the TSH receptor in vitro and may be one of the action mechanisms of lithium on the thyroid gland.

Cell Membrane↗
PubMed1989

Anaplastic thyroid carcinoma: review of 24 cases, with emphasis on cytodiagnosis and leukocytosis.

Twenty-four cases of anaplastic thyroid carcinoma seen in the National Taiwan University Hospital from 1980 to 1988 were reviewed. The median age was 61.5 years. The ratio of men to women was 1:1.4. A preceding history of long-standing goiter could be obtained in 14 patients (58.3%) with a median duration of 20 years. Twenty patients (83.3%) presented with a rapid-growing neck mass with a median duration of 1.3 months. Nine out of 19 patients (47.4%) had white blood cell (WBC) counts over 10,000/microliters, which were closely related to the presence of fever (p less than 0.02). Serial follow-up showed that WBC and platelets gradually increased but red blood cells and hemoglobin decreased. Fever was noted at the time of diagnosis in 8 out of 24 patients (33.3%), and was closely related to the presence of abundant neutrophils in the cytologic smears of thyroid aspirates (p less than 0.01). Fever was not due to bacterial infection. Three out of 10 patients (30.0%) had calcification in the thyroid shown on neck X ray, and 7 out of 18 patients (38.9%) had lung metastasis shown on chest X ray. The ultrasonographic images of thyroid anaplastic carcinoma done in 6 patients were heterogeneous and hypoechoic. Fine-needle aspiration cytology was done in 20 patients. Anaplastic thyroid carcinoma was easily diagnosed in 18 patients (90.0%). One was misdiagnosed as acute thyroiditis. Another one was diagnosed as papillary carcinoma cytologically, which combined with anaplastic carcinoma shown on histology. The median survival was 2.2 months, ranging from 0.2 to 25.3 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Reversible dissociation of the catalytically active subunits of pigeon liver malic enzyme.

The pH-induced reversible dissociation of pigeon liver malic enzyme (EC 1.1.1.40) was studied by combined use of chemical cross-linking and SDS/polyacrylamide-gel electrophoresis. The tetrameric enzyme showed a pH-dependent dissociation in an acidic environment. At pH values above 8.0 most molecules existed as tetramers. The enzyme was gradually dissociated at lower pH. When the pH was below 5.0 most of the enzyme was present as the monomeric forms. Reassociation of the subunits was accomplished by adjusting the pH to neutrality. The dissociation and reassociation were almost instantaneous. No trimer was detected. The pigeon liver malic enzyme was thus shown to have a double-dimer quaternary structure with D2 symmetry. In the presence of substrates, the monomer-dimer-tetramer equilibrium favours the direction of dissociation. Tartronate, an L-malate analogue, was found to be more effective than L-malate in this process. When the monomeric forms were immobilized, the enzyme subunits were found to be fully active in catalysis. A possible arrangement of the four identical subunits of the enzyme molecule is proposed to account for the results obtained in this investigation. The origin of the half-of-the-sites reactivity of pigeon liver malic enzyme is also discussed.

Animals↗
PubMed1988

Approaches to protection against nerve agent poisoning. (Naphthylvinyl)pyridine derivatives as potential antidotes.

Analogues of the potent inhibitor of choline acetyltransferase (CAT) (E)-4-(1-naphthylvinyl)pyridine methiodide were synthesized and evaluated for their ability to inhibit CAT and protect against nerve agent intoxication. Several compounds, notably (E)-1-(2-hydroxyethyl)-(1-naphthylvinyl)pyridinium bromide (3), (E)-1-methyl-4-(1-naphthylvinyl)-1,2,3,6-tetrahydropyridine hydrochloride (22), and (E)-1-methyl-4-(1-naphthylvinyl)piperidine hydrochloride (23), were found to afford significant protection against sarin in the mouse and against soman in the guinea pig. However, protection was apparently not related to CAT inhibition. Compound 23, our most effective compound in protecting against nerve agent, was without CAT inhibitory activity. Compound 22, which proved to be a potent CAT inhibitor, most likely owed this activity to being dehydrogenated back to the pyridinium quaternary salt by oxidative enzymes. Several of the (naphthylvinyl)pyridine quaternary salts, but not their tertiary amine analogues, were found to be effective in slowing the rate of aging of soman-inhibited acetylcholinesterase. Ability to slow the rate of aging was enhanced by introduction of methoxy substituents on the aryl moiety whereas the aging rate was actually accelerated by chloro substituents. To date, our most effective compound in slowing the rate of aging, (E)-4-[(4-methoxy-1-naphthyl)vinyl]pyridine methochloride (6), did not provide significant protection against soman in the mouse.

Acetylcholinesterase↗
PubMed1988

Starch Phosphorylase Inhibitor Is beta-Amylase.

The proteinaceous noncompetitive inhibitor of starch phosphorylase isolated from the root of sweet potato (Ipomoea batatas [L.] Lam.) (TC Chang, JC Su 1986 Plant Physiol 80: 534-538) has been identified as a beta-amylase. The starch phosphorylase inhibitor and beta-amylase activities copurified to give a protein indistinguishable from commercial beta-amylase by electrophoretic and immunological methods, and the two activities showed parallel responses in pH, temperature, and inhibitor sensitivity tests. The amylolytic pattern of the inhibitor corresponded to that of beta-amylase and its inhibitory effect toward starch phosphorylase was due to neither deprivation of starch, the primer for the phosphorylase assay, nor the inhibitory effect of amylolytic products.

Journal Article↗
PubMed1988

Cell kinetics, DNA content and TSH receptor-adenylate cyclase system in differentiated thyroid cancer.

The purpose of this study was to elucidate the changes of the TSH receptor-adenylate cyclase system in differentiated thyroid carcinomas, and their relationships with nuclear DNA content, cell kinetics and clinical stage. The results showed that the papillary carcinomas had an impaired TSH receptor-adenylate cyclase system. The production of cAMP stimulated by TSH was decreased when compared with non-cancerous tissue and high-affinity TSH receptors were reduced in number or even completely lost (nine in 24 cases). Follicular carcinomas also showed a reduction in, or even complete loss, of high-affinity TSH receptor (one in five cases). However, the responses to the stimulation of TSH, Gpp (NH)p and forskolin were not different from those in non-cancerous tissue. Papillary and follicular cancer cells showed more proliferative activity than those in non-cancerous tissue. Follicular carcinomas contained more hyperploid cells (DNA content greater than 2.5 C) than papillary carcinomas. There were no differences in cell kinetics, DNA content or the effects of Gpp (NH)p or forskolin on adenylate cyclase activity between those papillary carcinomas with high-affinity TSH receptor and those without. However, the presence of high-affinity TSH receptors had higher cAMP generation stimulated by TSH. The patients having papillary carcinomas in the absence of high-affinity TSH receptors were all in clinical stage III. These studies suggest that TSH receptors are the major sites influenced in the TSH receptor-adenylate cyclase system in papillary carcinomas. The TSH receptor-adenylate cyclase system of papillary carcinomas differs more from normal than does that of follicular carcinomas.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗