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Biomedical subjects

C H Chang

Publications and source records attributed to C H Chang.

At least 613 records · Page 34Linked to original sources
PubMed1983

Biochemical analysis and electron microscopy of human mitral valve collagen in patients with various etiologies of mitral valve diseases.

Biochemical analyses and electron microscopy of mitral valve collagen were carried out in 29 patients with various mitral valve diseases. They were divided into 3 groups: (1) rheumatic heart disease (15 patients), (2) isolated rupture of chordae tendineae (8 patients), and (3) floppy mitral valve (6 patients). Normal mitral valves obtained at necropsy from 6 patients who died from extracardiac causes were used for control observations. Results of the electrophoretic analysis of the collagen of normal and diseased valves showed that all valves contained collagen types I, III, and AB collagen with similar electrophoretic patterns. Electron microscopic observations and comparisons of the segment-long-spacing crystallites of each type of collagen revealed similar band patterns, irrespective of the normal or diseased valves sources. It is concluded that the composition and primary molecular structure of mitral valve collagen are usually not altered in a wide variety of disease processes affecting the mitral valve.

Adolescent↗
PubMed1983

Computed tomographic mammography directed biopsy of the breast.

Computed tomography of the breast has been demonstrated to identify nonpalpable carcinoma of the breast at an early stage. It has been found possible to do an accurate biopsy of these small tumors using azimuth and distance data provided by the radiologist.

Biopsy↗
PubMed1982

Light-induced nicking of deoxyribonucleic acid by cobalt(III) bleomycins.

The anticancer drug bleomycin is a glycopeptide that causes strand scission of DNA both in vivo and in vitro. Cleavage of DNA by bleomycin has been studied extensively in vitro, with the findings that ferrous ion and molecular oxygen must be present and that addition of reducing agents greatly enhances the reaction. To date, only iron has been shown to be an effective metal cofactor for the cleavage of DNA by bleomycin. Here it is reported that two stable cobalt(III) complexes of bleomycin are strikingly effective in causing single-strand breaks (nicks) in supercoiled DNA in the presence of ultraviolet or visible radiation. For example, 366-nm light from an 18-W long-wavelength mercury lamp for 1 h causes 10(-6) M cobalt(III) bleomycin to completely convert supercoiled phi X174 DNA (10(-8) M DNA, 10(-4) M phosphate) into the nicked circular form. Furthermore, numerous alkali-labile sites are produced on the DNA during this treatment. The observed reactions are not caused by adventitious iron, and they occur only in the presence of cobalt(III) bleomycin and light.

Bacteriophage phi X 174↗
PubMed1982

Purification and characterization of androgen receptor from steer seminal vesicle.

The androgen receptor has been purified from steer seminal vesicle cytosol by a combination of differential DNA-Sepharose 4B chromatography and testosterone 17 beta-hemisuccinyl-3,3'-diaminodipropylamine-Sepharose 4B affinity chromatography. The procedure produced about 3 micrograms of receptor protein from 35 g of steer seminal vesicle, with a yield of 48%. The receptor protein, as a complex with unlabeled testosterone, was purified approximately 540000-fold. A single band, migrating at 60000 daltons, was observed following electrophoresis on a polyacrylamide gel containing sodium dodecyl sulfate (NaDoDSO4). This was confirmed by affinity labeling of the partially purified receptor with both 17-hydroxy-17 alpha-[3H]methyl-4,9,11-estratrien-3-one and 17 beta-hydroxy-[1,2,4,5,6,7,16,17-3H8)-5 alpha-androstan-3-one 17-(2-bromoacetate), which showed a peak of radioactivity migrating at 60000 daltons by NaDoDSO4 gel electrophoresis. The receptor had an estimated Stokes radius of 35 A and a sedimentation coefficient of 3.8 S in the presence of 0.3 M NaCl. The calculated molecular weight and frictional ratio for the androgen binding activity were 57000 and 1.42, respectively. Chromatofocusing of the purified receptor protein revealed an isoelectric point of 6.6. [3H]Methyltrienolone, bound to the purified receptor, was displaced with methyl-trienolone greater than testosterone greater than 5 alpha-dihydrotestosterone much greater than 3 beta-hydroxy-delta 5-androsten-17-one much greater than 5 alpha-androstane-3 alpha,17 beta-diol. The physicochemical properties of the purified receptor were similar to those of the receptor in crude cytosol. These results demonstrate that the androgen receptor from steer seminal vesicle was substantially purified without significant modification of its physicochemical or steroid binding properties.

Affinity Labels↗
PubMed1982

Rotational mobility of an erythrocyte membrane integral protein band 3 in dimyristoylphosphatidylcholine reconstituted vesicles and effect of binding of cytoskeletal peripheral proteins.

Band 3 protein was isolated from human erythrocyte membranes, purified, and reconstituted into a well-defined phospholipid bilayer matrix (dimyristoylphosphatidylcholine). The preparation yielded uniform single-bilayered vesicles of the diameter 40--80 nm. The rotational motion of band 3 was studied by saturation transfer electron spin resonance (ESR) spectroscopy of covalently attached maleimide spin-labels. The rotational mobility changed in response to the host lipid phase transition. The rotational correlation time was in a range from 73 (37 degrees C) to 94 microseconds (26 degrees C) in the fluid phase and from 240 (15 degrees C) to 420 microseconds (5 degrees C) in the solid phase. The motion was analyzed based on the anisotropic rotation of band 3 in the reconstituted vesicles. To obtain information on the rotational diffusion constant around the axis parallel to the membrane normal, we made an attempt to measure the angle between the spin-label magnetic axis and the membrane normal. The result gave 3.9 x 10(4) s-1 at 37 degrees C as a rough estimate for the diffusion constant. This is compatible to anisotropic rotation of a cylinder of radius 3.3 nm in a two-dimensional matrix with inner viscosity 2 P and inner thickness 4 nm. The cytoskeletal peripheral proteins caused a definite increase in the rotational correlation time (from 73 to 180 microseconds at 37 degrees C, for example). The restriction of the rotational mobility was shown to be due to the ankyrin-linked interaction between band 3 and spectrin-actin-band 4.1 proteins in the reconstituted membranes.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1982

Cerebellar hemangioblastomas.

Between 1950 and 1976, 24 patients with cerebellar hemangioblastomas received postoperative radiation therapy. In retrospect, the low-dose radiotherapy that was practiced in the 1950s and early 1960s has been associated with inferior survival rates. Since 1963 and with increased awareness of the effects of radiotherapy, patients receiving high-dose irradiation postoperatively have generally survived longer. Postoperative radiotherapy is used whenever the neoplasm has not been totally excised. This more likely to occur with solid hemangioblastoma and neoplasms arising in the brain stem. In addition, radiotherapy should be used when the tumor recurs after total excision. The recommended dose is in the range of 4500--5000 rads in 4 1/2--5 weeks.

Adolescent↗
PubMed1982

Familial T-cell lymphoblastic lymphoma: association with Von Recklinghausen neurofibromatosis and Gardner syndrome.

A family is described in which three of seven siblings developed a T-cell lymphoblastic lymphoma. Tumor cells formed rosettes with sheep erythrocytes, lacked surface Ig, and expressed human T- but not B-lymphocyte antigens. They lacked the enzyme terminal transferase suggesting a lymph node rather than thymic T-cell origin. Autopsy findings supported this conclusion. All three sibs, like their father, had numerous cafe'-au'lait spots indicative of Von Recklinghausen neurofibromatosis. One child had a subcutaneous fibroma, and another had multiple colonic polyps and exostoses characteristic of Gardner syndrome. Both are autosomal dominant conditions known to predispose to malignancies. The genetic factors responsible for these conditions may also predispose to the development of "post-thymic" T-cell lymphoblastic lymphoma.

Child↗
PubMed1982

A lethal, Larsen-like multiple joint dislocation syndrome.

We describe here two isolated cases of lethal, Larsen-like multiple joint dislocation syndrome. Death occurred shortly after birth with pulmonary insufficiency due to tracheomalacia and/or lung hypoplasia. Both had abnormal dermal collagen bundles. In one case, histochemical studies showed abnormal cartilagenous matrix and striking deficiency in the dense collagen bundles of joint capsules; electronmicroscopic studies of the hyaline cartilage of the trachea documented a relative increase of the small, short fibers with decrease of the matrix collagen fibers. This study confirms that this Larsen-like syndrome is a disorder of connective tissue, possibly involving dysmaturity of the collagen fibers, with a predilection for joint capsules and tracheal cartilage. This lethal condition is characterized by pulmonary insufficiency, tracheomalacia, and collagen fiber dysmaturity.

Collagen Diseases↗
PubMed1982

Congenital primitive neuroectodermal tumor (neuroepithelioma) of the chest wall.

Primitive neuroectodermal tumor (neuroepithelioma) is a relatively common central nervous system tumor in children. Those arising from a peripheral nerve are extremely rare in childhood. There is only one reported case in 6-year-old where the tumor arose from the sciatic nerve. A case of neuroectodermal tumor of the chest wall, arising from the intercostal nerve, in a newborn is presented. The tumor metastasized to the brain. Prominent Homer-Wright rosettes, with central eosinophilic fibrillar substance similar to that seen in neuroepithelioma of the central nervous system, were present in the primary tumor and brain metastases. Ultrastructure, as revealed by transmission electron microscopy, is also described.

Brain Neoplasms↗
PubMed1982

Thyrotoxicosis and thyroid cancer.

It is generally held that thyroid cancer is uncommonly associated with thyrotoxicosis. We report here nine patients with thyroid cancer amongst 720 patients with thyrotoxicosis. Three patients presented with features of malignancy together with thyrotoxicosis (Group A), one of whom had triiodothyronine (T3)-toxicosis. The remaining six patients were diagnosed following histological examination of tissues removed during subtotal thyroidectomies for hyperthyroidism (Group B). Two patients in Group A had follicular carcinoma; the rest were papillary in type. All the patients were rendered euthyroid initially, followed by ablative therapy for two patients in Group A and four patients in Group B. All but one are alive after one to nine years (mean of 3 . 4 years). The diagnosis of thyroid carcinoma is infrequently considered in the presence of thyrotoxicosis. The association is not clinically apparent in the majority of patients. The optimum management of such occult malignancies in thyrotoxicosis remains to be defined.

Adenocarcinoma↗
PubMed1982

Craniopharyngiomas in children.

Forty-three children with craniopharyngiomas were operated upon at The Neurological Institute of New York between 1952 and 1977. The removal was thought to be total in 14 children and subtotal in 20, and cyst aspiration/biopsy was performed in 9 cases. Radiation was given as part of the initial therapy in 6 children after subtotal removal and to 8 others after aspiration/biopsy. There was 1 postoperative death. All children with tumors thought to have been removed totally are alive. The 10-year actuarial survival rates are 52% for subtotal removal alone and 87% for subtotal removal plus radiation. Tumors have recurred by 10 years in half of those thought to be totally removed, in more than 90% of those subtotally removed, and in less than 25% of those at risk after subtotal removal and radiation therapy. Tumors recurred in 22 children, and 17 underwent reoperation. Total removal was obtained in 4 cases, and 5 had radiation after subtotal removal. Radiotherapy alone was used in 2 cases. Recurrences usually occurred within 2 years. However, after "total" removal recurrences were quite delayed. Our data indicate that total removal allows excellent survival rates and that some of these children are potentially cured. The attempt at total removal did not inflict a severe hypothalamic or visual burden on these children. Where total removal is not possible, further therapy, either radiation or reoperation, will be required. Radiation dramatically decreased recurrence and improved survival after subtotal removal.

Adolescent↗