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Biomedical subjects

C Y Chang

Publications and source records attributed to C Y Chang.

At least 235 records · Page 13Linked to original sources
PubMed1991

Fluid levels in aneurysmal bone cysts.

Aneurysmal bone cysts are benign, expansile, osteolytic lesions of the bone. All the aneurysmal bone cysts studied in this case report were observed during the 2 year period, 1989 to 1991. The patients involved had received radiographic examination: plain and magnetic resonance (MR) image; one of the patients also received a computed tomography (CT). The plain radiograph generally showed a well-defined, expansile, osteolytic lesion associated with a pathologic fracture; the CT and MR images showed a fluid-fluid level within the lesion. This paper will report the findings of fluid-fluid levels, using radiographic images, in aneurysmal bone cysts.

Adult↗
PubMed1991

[MRI of white matter pathways].

CT scan shows some relatively large white matter pathways such as corpus callosum or internal capsule, while MRI provides more sophisticated display of cerebral white matter pathways, based partly on difference in the water content, which improves contrast resolution of structures that cannot be appreciated on CT scanning. The white matter shows slightly high signal intensity in T1WI as compared with the peripheral gray matter. In contrast, it is relatively low signal intensity in long TR sequence. The signal intensity is correlated with myelination, density of myelin fibers and possibly iron deposition. In this study, we collected data on 30 patient, aged from 3 to 60 years average 38 years of normal MRI study of the brain. We routinely obtained T1 Weighted image (T1WI, TR/TE 500-600/20 msec), dual echoes image of proton density image (PDI, TR/TE 2000-3000/20 msec), T2 weighted image (T2WI, TR/TE 2000-3000/80-120 msec), in axial and coronal sections. In some cases sagittal section was also imaged. We identified the white matter pathways based on the data from the axial and coronal sections of 2 autopsy specimens. We also consulted several textbooks and literature reviews of gross and MRI anatomy. The following white matter pathways could be clearly observed on MRI: 1. Projection fibers: corona radiata and internal capsule; 2. Commissural fibers: corpus callosum and anterior commissure; 3. Associated fibers: superior occipito-frontal fasciculus, superior longitudinal fasciculus, ucinate fasciculus, cingulum bundle, optic radiation fornix and mammillothalamic tract.

Adolescent↗
PubMed1990

The lethal lambda S gene encodes its own inhibitor.

The 107 codon reading frame of the lambda lysis gene S begins with the codon sequence Met1-Lys2-Met3..., and it has been demonstrated in vitro that both Met codons are used for translational starts. Furthermore, the partition of initiation events at the two start codons strongly affects the scheduling of lysis. We have presented a model in which the longer product, S107, acts as an inhibitor of the shorter product, S105, the lethal lysis effector, despite the fact that the two molecules differ only in the Met-Lys residues at the amino terminus of S107. Using immunological and biochemical methods, we show in this report that the two predicted protein products, S105 and S107, are detectable in vivo as stable, membrane-bound molecules. We show that S107 acts as an inhibitor in trans, and that its inhibitory function is entirely defined by the positively charged Lys2 residue. Moreover, our data show that energy poisons abolish the inhibitory function of S107 and simultaneously convert S107 into a lysis effector. We propose a two step model for the lethal action of gene S: first, induction of the S gene results in the accumulation of S105 and S107 molecules in mixed oligomeric patches in the cytoplasmic membrane; second, S monomers rearrange by lateral diffusion within the patch to form an aqueous pore. The R gene product, a transglycosylase, is released through the pore to the periplasm, resulting in destruction of the peptidoglycan and bursting of the cell. According to this model, the lateral diffusion step is inhibited by the energized state of the membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

Alleles↗
PubMed1990

CT evaluation of polymorphic reticulosis.

For the understanding of the CT findings of polymorphic reticulosis involving the upper respiratory tract, we reviewed eleven cases of this disease with initial CT study before treatment. CT revealed masses or swelling in the nose or nasal chamber, often with involvement of paranasal sinuses and medial parts of the orbit. In some, nonspecific minimal bony change (either bone destruction or bone sclerosis) was found. These CT findings are not specific. Any large mass in the nose and nasal fossa with little associated bone destruction should, however, raise the differential diagnosis of polymorphic reticulosis.

Adolescent↗
PubMed1990

Structure, sequence, chromosomal location, and evolution of the human ferredoxin gene family.

Ferredoxin is an iron-sulfur protein that serves as an electron transport intermediate for mitochondrial cytochromes P450 involved in steroid, vitamin D, and bile acid metabolism. We cloned and characterized the human ferredoxin gene family, which includes two expressed genes and two pseudogenes. Sequence analysis of this gene family revealed that it encodes only one protein product. The expressed genes were assigned to chromosome 11 and pseudogenes to chromosomes 20 and 21 by identifying single-copy probes from each gene segment and hybridizing them to DNA from rodent-human hybrid cells. The pseudogenes lacked introns and contained numerous mutations, including insertion, deletion, and substitution which rendered them inactive. They were 96% and 85% homologous to the expressed gene, yet they were only 78% homologous with each other. The intronless nature, higher diversity among themselves, and distinct chromosomal location of the pseudogenes suggests that they arose by independent, retroposon-mediated events.

Amino Acid Sequence↗
PubMed1990

Granulosa cell tumor of the ovary.

In the past 20 years, approximately half of the 25 women with granulosa cell tumor of the ovary studied, were dead. The results showed that recurrence or metastasis had a statistically significant correlation with survival. The other factors, such as the patients' age, the content of the tumor, ascites, endometrial change, mitosis and rupture, have no relationship with the survival rate in our study.

Adolescent↗
PubMed1989

Hyperparathyroidism presenting as a large bone tumour. A case report.

A 59-year-old man, who presented to hospital with a large expansile bone tumour over the left elbow and a mass in the right side of the neck, was eventually found to have parathyroid adenoma manifesting clinically as severe hypercalcaemia. Histological examination of a section of the neck mass showed parathyroid adenoma and the bone biopsy specimen revealed a 'brown tumour', consistent with hyperparathyroid bone disease.

Adenoma↗
PubMed1989

Analysis of the human adrenodoxin promoter: evidence for its activity.

Adrenodoxin is an iron-sulfur protein serving as an electron transfer intermediate in the mitochondrial cytochrome P450 system. To study its transcriptional regulation we construct a human adrenodoxin genomic clone which includes 333 bp of DNA upstream of the mRNA start site. This DNA contains a TATA box and two GC boxes. When we place it in front of the CAT reporter gene and transfect it into the recipient cell lines, it directs transcription of the CAT gene. This DNA in reverse orientation does not show any transcriptional activity. This promoter element functions in three mammalian cell lines: JEG-3, COS-1, and Y-1.

Adrenodoxin↗
PubMed1989

Temporary complementation of temperature-sensitive mutants of the cell cycle by transfection with a wild-type or a mutant cDNA of ADP/ATP translocase.

A number of cell-cycle-specific temperature-sensitive (ts) mutants have been isolated from animal cells, especially Syrian hamster cells. These ts mutants, like cell cycle ts mutants of yeast, can be complemented by specific genes, some of which have been molecularly cloned. We have isolated a cDNA clone that complements TK-ts13 cells, but only temporarily. This clone, called B1, differs from a previously isolated clone (Sekiguchi et al.: EMBO Journal 7:1683-1687, 1988) that specifically complements ts13 cells. In addition, B1 also complemented temporarily three other ts mutants of the cell cycle, tsAF8, ts694, and ts550C cells. These mutants have different mutations since, in cell fusion experiments, they complement each other. Sequencing of the B1 cDNA clone revealed that it was a mutant of human ADP/ATP translocase in which some human sequences at the 5' end have been replaced by SV40 sequences. The wild-type translocase was less effective but could still increase the survival time of cell cycle ts mutants at the restrictive temperature. Using the polymerase chain reaction, it was possible to demonstrate that the B1 plasmid is expressed in TK-ts13 cells undergoing temporary complementation.

Amino Acid Sequence↗
PubMed1989

Maternal serum alpha-fetoprotein screening in Taiwanese women.

From January 1986 to August 1988, a maternal serum alpha-fetoprotein (MSAFP) screening program was performed at Mackay Memorial Hospital. Clinical Assay Gamma Dab [I125] AFP RIA Kit (Baxter U.S.A.) was used for the quantitative measurement of AFP in maternal serum. Between 16 and 25 gestational weeks, MSAFP above the cut-off value at 2.5 multiples of the median was able to detect 5/7 cases of anencephalus, 2/4 cases of encephalocele, 3/3, cases of omphalocele, 11/40 cases of twin pregnancies. Among 10 cases with autosomal trisomies, 8/10 were less than 0.6 multiples of the median and 4/10 were less than 0.4 multiples of the median.

Adult↗
PubMed1989

Routine pretreatment evaluation in cervical carcinoma.

A review of 573 previously untreated patients with invasive cervical carcinoma was undertaken to determine the significance of the routine pretreatment performance of chest x-ray, intravenous pyelography (IVP), cystoscopy and sigmoidoscopy. Chest x-ray was performed in 570 patients (99.5%), IVP in 514 (89.7%), cystoscopy, 502 (87.6%) and sigmoidoscopy, 496 (86.6%). The overall yield of tumor-related abnormalities demonstrated in chest x-ray, IVP, cystoscopy and sigmoidoscopy was 1.8%, 9.1%. 6.4% and 1.2% respectively. The chest x-ray findings changed the initial clinical stage in 1.3% of cases, IVP in 4.2%, cystoscopy in 4.0% and sigmoidoscopy in 0.6%. There were 5 instances of bladder involvement and 5 of bullous edema of the bladder found in patients originally classified as having stage I or stage II disease. Thus, to omit cystoscopy may not be so safe in patients with stage I and stage II diseases. We suggest that chest x-ray, IVP and cystoscopy should be performed as part of staging in all patients with cervical carcinoma, however, sigmoidoscopy can be reserved for those initially diagnosed to have advanced disease or symptomatic patients.

Carcinoma↗
PubMed1988

Cloning and structure of the human adrenodoxin gene.

Adrenodoxin is an iron-sulfur protein that serves as an electron transport intermediate for all mitochondrial forms of cytochrome P450. To facilitate studying the regulation of adrenodoxin, we have cloned and determined the structure of the human adrenodoxin gene. It spans more than 20 kb, containing four exons and three introns. The first exon encodes the 60-amino-acid signal peptide, directing transport of the protein into the inner mitochondrial matrix. The mature peptide of 124 amino acids is encoded by the other three exons. The third exon encodes the portion of the protein containing the iron-sulfur center and a domain which binds other components of the electron transport chain. The transcriptional start sites were determined by primer extension and S1 nuclease mapping. The 5'-flanking region of this gene contains canonical promoters including a TATA box at nucleotide position -30 and two GC boxes at nucleotide positions -60 and -100. The sequence at nucleotides -234 to -252 is also highly homologous to the glucocorticoid-responsive element and the estrogen-responsive element.

Adrenodoxin↗
PubMed1988

Assignment of the functional gene for human adrenodoxin to chromosome 11q13----qter and of adrenodoxin pseudogenes to chromosome 20cen----q13.1.

Adrenodoxin is a small iron/sulfur protein serving as an electron-transport intermediate for all mitochondrial forms of cytochrome P450. Southern blots of normal genomic DNA cleaved with six restriction endonucleases probed with full-length human adrenodoxin cDNA revealed complex patterns indicating the presence of multiple adrenodoxin genes. Southern blots of DNA from a panel of mouse/human somatic cell hybrids identified cross-hybridizing adrenodoxin DNA in two loci, chromosome 11q13----qter and chromosome 20cen----q13.1. Examination of adrenodoxin clones from a genomic DNA library in phage lambda revealed some clones bearing gene fragments interrupted by introns and other clones bearing processed pseudogenes. By probing the mouse/human hybrids with unique intronic DNA and by correlating restriction maps of the phage clones with that of uncloned genomic DNA, we show that the authentic transcribed adrenodoxin gene lies on chromosome 11, while pseudogenes lie on chromosome 20.

Adrenodoxin↗