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Biomedical subjects

C H Chang

Publications and source records attributed to C H Chang.

At least 649 records · Page 36Linked to original sources
PubMed1981

Thyroid scanning & the significance of the solitary cold nodule.

Since thyroid scanning was introduced in Singapore in 1968 there has been progressive increase in the demand for these scans. 215 patients comprising 153 females and 62 males were scanned in 1976 using 131I. The solitary nodule was the commonest condition referred for scans (60%) and next was the multinodular goitre 919%). Other indications for scan included postthyroidectomy cases, aberrant thyroids, retrosternal goitres, thyrotoxicosis and metastases from thyroid carcinoma. 73 cases of solitary cold nodules were discovered and 43 of these were operated on. 7 of these were found to be malignant, giving an incidence of 16%. The incidence of malignancy in the cold nodule varies in the reported literature. By itself the 131I scan cannot diagnose malignancy but is it a useful supplementary test in addition to the clinical and other investigations.

Adult↗
PubMed1980

Computed tomography in detection and diagnosis of breast cancer.

From October 1, 1976 through July 31, 1979, at the University of Kansas Medical Center, CT/M examinations were performed on 1625 patients. Seventy-eight cancers were histologically diagnosed. A CT/M study using our contrast medium enhancement technique yields both static anatomical changes and dynamic measurements of abnormal iodide concentrations in the breast cancers. This unique ability of CT/M provides many advantages as compared with conventional mammography in the diagnosis of breast cancer. The detection rate in 78 cancers by CT/M was 94% and 77% for the mammography. The CT/M appears to be specially superior to the mammography for detecting cancers in dense, premenopausal dysplastic breasts. The CT/M can detect totally unsuspected very small breast cancers that were unable to be identified by conventional mammography or physical examinations. The CT/M scan also seems to be a better test for recognizing precancerous high risk lesions. CT/M evaluation affords definitive diagnostic help in instances where the mammographic and/or physical examinations are inconclusive. Although CT/M will not replace conventional mammography in routine breast examinations, it overcomes the limitation of mammography.

Breast↗
PubMed1980

Multiple pterygium syndrome.

We describe a sporadic case and four sibs from a consanguineous Nicaraguan family affected with the multiple pterygium syndrome. Clinical manifestations included normal intelligence; short stature; pterygia of neck, axillary, antecubital, popliteal, digital, and intercrural areas; multiple joint contractures with a crouched stance; a flat, sad, motionless facial appearance; and cleft palate. Males had small penis and scrotum and cryptorchidism; females had apparent aplasia of labia majora and small clitoris. Skeletal anomalies included fusion of cervical vertebrae, scoliosis, flexion contractures of fingers and "rocker-bottom" feet with vertical talus. This review documents genetic heterogeneity: Autosomal recessive inheritance in many cases, autosomal dominant determination in others, and sporadic occurrence.

Abnormalities, Multiple↗
PubMed1980

Determination of thyroxine binding globulin (TBG) in human serum by fluorescence excitation transfer immunoassay.

Human thyroxine binding globulin (TBG) was purified to near homogeneity by chromatography on thyroxine-substituted Sepharose 4B, DEAE-Sephadex A-50, Sephadex G-150 and n-decylamine-substituted Sepharose 4B. TBG was quantitated by homogeneous fluorescence excitation transfer immunoassay; the preparation of dye-protein conjugates is described. The fluorescence of fluorescein-TBG is quenched when an immune complex is formed with tetramethylrhodamine-antibody. In the presence of unlabeled TBG, the relative fluorescence intensity is increased and can be related quantitatively to the concentration of competing antigen. The described assay for TBG has a range corresponding to serum concentrations of 5--75 microgram/ml; the correlation with radioimmunoassay is 0.96. The coefficients of variation for replicate determinations of single samples of serum with low, normal and elevated TBG concentrations were 3.5%, 2.7% and 2.6% respectively; between-assay variations were 8.8%, 8.6% and 2.6% respectively.

Fluorescent Antibody Technique↗
PubMed1980

Prolactin and luteinizing hormone (LH) release throughout the postpartum period in the suckled first-calf beef cow.

A study was performed to examine the release patterns of prolactin and LH of young beef cows with one (single calf) or two calves (double calf) throughout the postpartum interval. The effect on prolactin release of intramuscular and intra-carotid administration of lergotrile and intra-carotid administration of L-dopa was also examined. In approximately 50% and 65% of the cases, no prolactin release could be detected after the beginning of or during the suckling stimulus in cows with one or two calves respectively. LH plasma concentrations remained constant throughout the experiment in all animals. The chosen intramuscular lergotrile treatment lowered plasma prolactin concentrations to baseline levels but had no effect on the length of the postpartum interval. No effect on prolactin release was observed by the given intra-carotid treatments of both lergotrile and L-dopa. First postpartum estrus was observed on days 67 and 88 in the single and double calf cows respectively. The number of suckling periods did not change during the postpartum period but their duration decreased during the same period. These results demonstrate that in at least half of the cases the suckling stimulus does not cause a release of prolactin from the pituitary in the young beef cow. Also, the inhibitory effect of suckling on the resumption of ovarian cyclic function postpartum appears to be of a quantitative nature and mediated by a factor other than prolactin.

Journal Article↗
PubMed1980

Comparison of cytosolic and mitochondrial hepatic enzyme alterations in Reye's syndrome.

The activities of nine enzymes in liver specimens obtained from four children who had died from Reye's syndrome were compared to the corresponding activities of a control group of four children who had died from unrelated causes. At the 95% significance level, the alterations could be classified into three groups. Five activities [lactate dehydrogenase, alanine aminotransferase, glucose 6-phosphatase, cytochrome oxidase, and malate dehydrogenase (mitochondrial plus cytosolic)] showed no change. Three enzymes [glutamate dehydrogenase, isocitrate dehydrogenase (NADP), and monoamine oxidase] were decreased. One activity (glucose 6-phosphate dehydrogenase) was increased. The malate dehydrogenase isozymes were resolved by electrophoresis, and the two bands were stained and measured. The ratio of cytosolic:mitochondrial enzyme was significantly greater in Reye's syndrome than in the control group. These results lend further support to the view that in Reye's syndrome the impairment of hepatic function is largely confined to the mitochondria. The lowered activity of monoamine oxidase means that the abnormalities extend to the outer mitochondrial membrane. Imbalances of the cytosolic:mitochondrial enzyme activities were evaluated in needle biopsy specimens from four other children under conditions where neurologic abnormalities were less severe. Two patients had elevated ratios of both glutamate:lactate dehydrogenase and cytosolic:mitochondrial malate dehydrogenase activities, and a third had only an abnormal malate dehydrogenase ratio. In contrast to these Reye's syndrome patients, a fourth case admitted with a provisional diagnosis of Reye's syndrome showed no abnormality in either ratio in stage IV coma.

Adolescent↗
PubMed1980

Presence of the rare D-variant heat-stable, placental-type alkaline phosphatase in normal human testis.

In 11 adult testes studied, about 0.3 to 4.6% of the total alkaline phosphatase activity was heat stable and L-phenylalanine sensitive but L-homoarginine insensitive. The testicular heat-stable enzyme was more susceptible to inhibition by L-leucine and ethylenediaminetetraacetate than were the normal placental and intestinal enzymes. By antibody-directed enzyme inhibition test, the testicular heat-stable enzyme cross-reacted completely with normal placental enzyme but clearly distinguished itself from a heat-stable component of normal intestinal enzyme. Thus, placental alkaline phosphatase D-variant is synthesized in testis, indicating that the gene for elaborating this placental protein is probably already active in the testicular cells. The high incidence of this protein in cancers of testis and ovary is probably due to its increased production by gonadal genes present in the genome of these particular tumors.

Alkaline Phosphatase↗
PubMed1980

Effects of deoxyadenosine triphosphate and 9-beta-D-arabinofuranosyl-adenine 5'-triphosphate on human ribonucleotide reductase from Molt-4F cells and the concept of "self-potentiation".

Deoxyadenosine triphosphate (dATP) acted as a noncompetitive inhibitor with respect to the specific nucleoside triphosphate activator for the reduction of all four common ribonucleoside diphosphates catalyzed by the reductase derived from human Molt-4F (T-type lymphoblast) cells. The inhibition constant of dATP for different ribonucleotide reduction reactions was different, indicating that the binding of the nucleoside triphosphate activator or substrate could modify the binding affinity of dATP to the enzyme. dATP also acted as a noncompetitive inhibitor with respect to cytidine diphosphate (CDP) for reductase-catalyzed CDP reduction. 9-beta-D-Arabinofuranosyl-adenine 5'-triphosphate acted as a competitive inhibitor with respect to either adenosine triphosphate or guanosine triphosphate for CDP or for adenosine diphosphate reduction, respectively. The inhibition constant was 15 microM for CDP reduction and 4 microM for adenosine diphosphate reduction. 1-beta-D-Arabinofuranosyladenine 5'-triphosphate could not substitute for adenosine triphosphate or guanosine triphosphate as the activator for CDP or adenosine diphosphate reduction, respectively. The effects of 9-beta-D-arabinofuranosylcytosine 5'-triphosphate and 5-iodo-2'-deoxyuridine 5'-triphosphate on ribonucleotide reductase were also included for comparison. The "self-potentiation" mechanism of the action of 9-beta-D-arabinofuranosyladenine and 5-iodo-2'-deoxyuridine is discussed.

Adenosine Diphosphate↗
PubMed1980

Cystadenoma of the pancreas with cytomegalovirus infection in a female infant.

Cystadenoma of the pancreas, principally a disease of adult women, was found in a female infant. This benign, nonfunctional tumor is usually amenable to surgery and a cure is to be expected after extirpation. The pathogenesis of this mass is unknown, but the finding of a cytomegalovirus infection in an excretory duct at the tumor base in this case leads us to speculate that obstruction of the excretory duct is a possible cause.

Cystadenoma↗
PubMed1980

Adriamycin in the treatment of resectible and irresectible primary hepatocellular carcinoma.

The treatment of 205 patients with primary hepatocellular carcinoma in Singapore from 1975 to 1980 is reviewed. Adriamycin given at a dose of 40 mg/m(2) intravenously every 4 weeks for irresectible tumours achieved a response rate of 32% alone and has significantly prolonged the median survival time to 4 1/2 months (135 days) in these individuals. Despite this response only 1/34 (3%) patient showed complete remission and is alive at 2 1/2 years. Use of other combinations with Adriamycin e.g. 5 Fluorouracil and Vincristine produced a significant response in the first 16 weeks (p < 0.005) but not thereafter, when completed with the historical group. To improve the response and to consolidate this response, split doses of total hepatic irradiation (to a maximum of 3,150 rads) and alternate day administration of intravenous Adriamycin 10 mg (to a maximum of 90 mg) were given. 12/23 patients (50%) responded. This was followed by a four weekly Adriamycin, 5 F.U. and Vincristine. Median survival time was 5 1/2 months (165 days). Relapse occurred in all patients. Similarly in 5 patients who had resections, early recurrences occurred in 3/5 (60%) within 3 months, inspite of postoperative chemotherapy with Adriamycin, 5 F.U., Vincristine and Cyclophosphamide given every four weeks. In view of the high recurrence rate following effective treatment, further studies on the biological behaviour of these abnormal livers is required.

Antineoplastic Agents↗