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Biomedical subjects

C H Chang

Publications and source records attributed to C H Chang.

At least 685 records · Page 38Linked to original sources
PubMed1978

Ultrastructural comparison between skeletal muscle and cardiac rhabdomyomas.

The electron microscope features of three primary cardiac rhabdomyomas and one skeletal muscle rhabdomyoma arising from the floor of the mouth are compared, along with a review of the previously reported ultrastructural features of skeletal rhabdomyomas. Cardiac rhabdomyoma filaments appear more orderly and have features suggestive of origin from both Purkinje and myocardial fibers. Zebra bodies were seen exclusively in the cardiac rhabdomyomas. In comparison, the extracardiac rhabdomyoma filaments were more disorderly and many cases had hypertrophic Z bands corresponding to the jackstraw or matchstick structures seen with the light microscope. This finding, along with the presence of satellite cells, was not seen in the cardiac rhabdomyomas.

Heart Neoplasms↗
PubMed1978

Specificity of computed tomography in the diagnosis of supratentorial neoplasms. Consideration of metastases and meningiomas.

A previously unsuspected linear relationship between the initial density and the amount of uptake of various tumors is described. As a rule, initially radiodense neoplasms enhance less than radiolucent neoplasms. For a given amount of enhancement, meningiomas are initially more radiodense than metastases; also, breast metastases are more radiodense than lung metastases. The density versus uptake curve tends to show certain specificity for a given type of neoplasm. Absolute differentiation of histologic types is still not possible on the basis of these curves. The correlation, however, is interesting and seems to be related to the amount of damage to the blood-brain barrier and the degree of calcification, vascularity, and cellularity of the various tumors. With improved precision of scanners the specificity of the CT image may be improved.

Brain Neoplasms↗
PubMed1978

The interactions of gallium with various buffers and chelating agents in aqueous solution: gallium-71 and hydrogen-1 NMR studies.

The interactions of gallium (Ga) with the ligands, EDTA, NTA, phosphate, lactate, MOPS, TRIS and HEPES are investigated using both 71Ga and 1H nmr measurements. Both EDTA and NTA form strong complexes with gallium, which have a 1:1 stoichiometry. In alkaline solution the tetrahedral Ga(OD)4- competes strongly with EDTA in complex formation. In the lactate complex, there are probably three lactates per gallium present. The phosphate complexes of gallium are difficult to characterize on the basis of this investigation. The buffers, MOPS, TRIS, and HEPES, do not interact with gallium significantly. The ability of the ligands to bind gallium correlates well with their ability to inhibit gallium incorporation by L1210 leukemic cells.

Buffers↗
PubMed1978

Midline pineal tumors and suprasellar germinomas: highly curable by irradiation.

Sixty-one patients with midline pineal tumors and 16 patients with suprasellar germinomas were treated with surgical decompression and relatively high-dose radiotherapy of the primary site. Results were excellent, and there were no long-term complications. Ten per cent of midline pineal tumors and 37% of suprasellar germinomas metastasized to the cerebral or spinal subarachnoid space within 6 months to 5 years. Irradiation of the entire neural axis is recommended for locally extensive tumors, simultaneous pineal and hypothalamic lesions, and all biopsy-proved germinomas. The five-year survival rate was 79% for midline pineal tumors and 77% for suprasellar germinomas.

Adolescent↗
PubMed1978

Preoperative diagnosis of potentially precancerous breast lesions by computed tomography breast scanner: preliminary study.

Eighteen cases of severe atypical epithelial hyperplasia of the breast were detected preoperatively by computed tomography breast scanner (CT/M) with contrast enhancement. The CT number before enhancement ranged from -17 to +31 and increased to 26 to 42 after enhancement (5.2-8.4% increase in attentuation). These data suggest that CT/M can differentiate these potentially precancerous lesions from benign fibrocystic disease.

Adult↗
PubMed1978

Muscle carnitine deficiency and fatal cardiomyopathy.

A 23-month-old boy with progressive muscle weakness and severe cardiomyopathy was found to have oil red O positive vacuoles predominantly in type 1 muscle fibers. Serum carnitine was normal, but muscle carnitine content was decreased. Both parents were clinically normal, but the muscle carnitine level was low in the father. Despite oral treatment with carnitine, the condition progressed and was fatal. At autopsy, cardiac muscle showed borderline low carnitine content and numerous mitochondria, but no lipid accumulation.

Cardiomyopathies↗
PubMed1978

Computed tomographic evaluation of the breast.

Experience with a dedicated breast CT scanner (General Electric CT/M) using a contrast medium enhancement technique indicates that CT is superior to mammography, thermography, or physical examination for diagnosing both benign and malignant mammary disease especially in dense, thick, or fibrocystic breasts. CT is capable of diagnosing totally unsuspected early miniature carcinomas. It can identify and differentiate potential precancerous lesions from benign fibrocystic disease, and is the diagnostic tool of choice for evaluating and following severe fibrocystic disease. CT evaluation also affords definitive diagnostic help in instances where the mammographic, thermographic, and/or physical examinations are inconclusive. It can influence immediate surgical intervention or mitigate against an unnecessary biopsy. The study not only demonstrates morphologic changes in the breast but also accurately depicts an altered iodine pool in mammary tissues.

Adult↗
PubMed1978

Effects of 1,10-phenanthroline and a zinc complex of 1,10-phenanthroline on nucleic acid synthesis in mouse liver and spleen.

The effects of 1,10-phenanthroline and a zinc complex of 1,10-phenanthroline on nucleic acid synthesis were examined by noting the capcity of these agents to incorporate [methyl-3H]thymidine, or [5-3H]uridine into hepatic and splenic DNA and RNA. Within 32 hours after the intraperitoneal injection of 1,10-phenanthroline in mice, a decrease of [methyl-3H]thymidine incorporation into hepatic DNA was observed. The administration of the zinc complex of 1,10-phenanthroline decreased the incorporation of [5-3H] uridine into hepatic RNA within 24 hours and decreased the formation of [3H]DNA from [methyl-3H]thymidine in the liver within 24 and 32 hours. An increase of the isotopic incorporation into hepatic RNA and of the pool size of ATP within 2 hours after the administration of the complex was also noted. In the splenic studies, the zinc complex significantly inhibited the formation of labeled DNA and RNA at 2, 8, 24, and 32 and 2, 8 and 24 hours postinjection, respectively. A relationship exists between the results obtained from sequential treatment (zinc chloride after 1,10-phenanthroline) and those derived from the zinc complex of 1,10-phenanthroline pertaining to an inhibition of isotopic incorporation into hepatic and splenic nucleic acid.

Adenine Nucleotides↗
PubMed1978

A case of generalized Wegener's granulomatosis in childhood: successful therapy with cyclophosphamide.

An 11-year-old white boy had Wegener's granulomatosis, a rare condition in the pediatric age group. The clinical course, pathological findings, and mode of treatment are outlined. The disease is in remission on a regimen of cyclophosphamide therapy as judged by both clinical and pathological criteria. This syndrome with protein manifestations should be considered in children with symptoms of repeated upper respiratory tract infections along with pulmonary and renal involvement. Early renal biopsy helps to establish the diagnosis of generalized involvement and to guide the course of treatment. Follow-up renal biopsies may serve as an indication for the continuation of treatment. Cytotoxic agents, especially cyclophosphamide, dramatically alter the course of the disease.

Child↗
PubMed1977

The effect of palmitoyl-coenzyme A on rat heart and liver mitochondria. Oxygen consumption and palmitoylcarnitine formation.

Rat heart and liver mitochondria, respectively, oxidized palmitoyl-CoA and palmitoylcarnitine optimally at 20-30 and 10-20 nmol substrate/mg. The oxidation of palmitoyl-CoA was accompanied by a lag in State 3 respiration that was proportional to the palmitoyl-CoA concentration. The delay in State 3 rates was more prolonged in liver than in heart at comparable palmitoyl-CoA levels. A similar range of palmitoyl-CoA concentrations produced significant inhibition of respiration in mitochondria oxidizing glutamate-malate. The inhibition was not due to a detergent effect of palmitoyl-CoA since addition of carnitine restored State 3 rates. Electron microscopic examination of mitochondria at low palmitoyl-CoA levels revealed normal ultrastructure. At comparable concentrations of palmitoyl-CoA, formation of palmitoylcarnitine by mitochondria from rat heart and liver followed first-order kinetics. The apparent first-order rate constants decreased with increasing palmitoyl-CoA. These results suggest that substrate inhibition may influence the rate of palmitoyl carnitine formation even at physiological concentrations of palmitoyl-CoA. The apparent first-order rate constant at palmitoyl-CoA levels (12 nmol palmitoyl CoA/mg) optimally oxidized by liver mitochondria, was one-third the value of the apparent rate constant measured in heart mitochondria at the identical substrate level. The prolongation in time to reach equilibrium may acocunt for the relatively greater respiratory sensitivity of liver mitochondria to increasing levels of palmitoyl-CoA.

Animals↗
PubMed1977

Osmium-labeled polynucleotides. The reaction of osmium tetroxide with deoxyribonucleic acid and synthetic polynucleotides in the presence of tertiary nitrogen donor ligands.

Osmium tetroxide in the presence of pyridine or 2,2'-bipyridine has been found to react completely with the pyrimidine moieties (thymine, uracil, and cytosine) in polynucleotides. Pyrimidine osmate ester moieties, L2OSO4-pyrimidine, were formed. The OSO4 has added across the 5,6 double bond and L=pyridine or 1/2-bipyridine. The pyridine derivatives were not stable and decomposed slowly after the OSO4-pyridine reagent was removed by gel chromatography. Labeled poly(uridylic acid) lost osmium completely during gel chromatography unless the eluent contained a high concentration of pyridine. The products formed between OSO4-bipyridine and polynucleotides were much more stable and the OS label was retained during and after gel chromatography. Both the OSO4-pyridine and OSO4-bipyridine reagents reacted more rapidly than the OSO4-CN-reagent.

Binding Sites↗
PubMed1977

Lymphopenia caused by cranial irradiation in children receiving craniospinal radiotherapy.

The peripheral blood changes were studied in 67 children who received craniospinal irradiation for posterior fossa tumors. At the completion of a cranial dose of about 3500 rad to the whole brain port, the lymphocytes were reduced to 858/mm3 rom 3084/mm3 preoperatively. The counts of the remaining leukocytes stayed at a level somewhat higher than preoperatively; the eosinophils rose to 288/mm3 from 125/mm3. With the initiation of the spinal field irradiation, which included a large proportion of the total bone marrow, the numbers of all the leukocytes decreased rapidly; the observed leukopenia was mainly secondary to neutropenia. A mechanism that was operating to restore the number of leukocytes became manifest immediately after the completion of radiotherapy, though the number of lymphocytes had not been totally restored to the preoperative level 6 years later. Irradiation of the lymphocytes that circulate through the vascular bed can explain the lymphopenia observed during cranial radiotherapy. Mild leukopenia observed in patients receiving radiotherapy through a relatively small port may be secondary to lymphopenia, and this does not necessarily indicate impaired bone marrow reserves.

Adolescent↗