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Biomedical subjects

S Wieder

Publications and source records attributed to S Wieder.

14 recordsLinked to original sources
PubMed1985

Regulatory factors specific for adult and embryonic globin genes may govern their expression in erythroleukemia cells.

In order to test if trans-acting regulatory factors specific for globin genes of the adult and embryonic stages of development exist in erythroid cells, transcriptionally active embryonic and adult globin genes on the same chromosome were transferred by cell fusion from the human leukemia cell K562 into phenotypically adult mouse erythroleukemia cells. Restriction-fragment-length polymorphisms of the K562 zeta (embryonic) globin genes were used to establish that all three copies of human chromosome 16 present in the K562 cell showed the same pattern of human globin gene expression after transfer to the mouse erythroleukemia cell. Adult (alpha) but not embryonic (zeta) human globin mRNA was detected in all nine of the independently derived mouse erythroleukemia hybrid cells, each of which contained human chromosome 16. Restriction endonuclease studies of the K562 alpha- and zeta-globin genes after transfer into the mouse erythroleukemia cell showed no evidence of rearrangements or deletions that could explain this loss of zeta-globin gene expression. These data suggest that regulation of globin gene expression in these erythroleukemia cells involves trans-acting regulatory factors specific for the adult and embryonic stages of development.

Animals↗
PubMed1982

Pulmonary artery occlusion due to histoplasmosis.

Histoplasma mediastinitis with complete or partial pulmonary artery obstruction due to compression and/or intraluminal granuloma was diagnosed in five patients and surgically verified in two. The patients, ages 12-27 years, had cough, dyspnea (four cases), and hemoptysis (two cases). Radionuclide imaging showed unilateral absence of pulmonary perfusion and minimal diminution of ventilation. Differentiation of this inflammatory process from other causes of ventilation-perfusion mismatch, for example, congenital hypoplasia and certain acquired causes of arterial obstruction, especially thromboembolism, may be possible by correlating radiographs, laminograms, and clinical history. Angiography can delineate the extent of perfusion impairment and may suggest its cause.

Adolescent↗
PubMed1981

Use of bacteriophage transposon Mu d1 to determine the orientation for three proC-linked phosphate-starvation-inducible (psi) genes in Escherichia coli K-12.

We have previously used the bacteriophage transposon Mu d1 (which encodes the lacZY structural genes but without their promoter) to construct strains that have lacZY fused to phosphate-regulated promoters in Escherichia coli K-12. Among 18 identified phosphate-starvation-inducible (psi) genes, three (the phoA and two new genes: psiF and psiG) are closely linked to the proC region. The gene order (clockwise) is phoA psiF proC psiG phoB phoR. Using these mutants containing Mu d1 insertions, we devised and tested a new method to determine their orientation. In this procedure, mutants with deletions that are selectable by their ability to grow at 42 degrees C are tested for the presence of Mu d1 and of neighboring genes. Some difficulties arose during analysis of suspected deletion-containing strains derived from Mu d1 lysogens (which also contained a Tn5 element) that were caused by Mu d1 and transposon transpositions and other possible genome rearrangements. Nevertheless, we have shown that the phoA and psiF genes are transcribed clockwise and the psiG gene is transcribed counterclockwise towards proC. Because phoA, but not psiF, gene expression requires the phoB+ (positive regulator) gene product, the phoA and psiF genes do not constitute an operon. On the other hand, the psiG:lacZ fusion-bearing strain may have a fusion to the promoter-distal end of the phoB gene. This implies that phoB expression is phosphate regulated. We believe that this method may be useful in general to elucidate the direction of gene transcription.

Chromosome Mapping↗
PubMed1981

Improved routine chest radiography with a trough filter.

Use of the aluminum trough filter for phototimed posteroanterior chest radiographs at 120 kVp provides excellent detail within the parenchyma of the lung as well as greatly enhanced visualization of mediastinal structures on a single exposure. An improvement in overall diagnostic value was noted by a panel of radiologists in 87% of 50 cases compared with conventional 120 kVp technique. Dosimetric measurements of the entrance exposure indicate a 12.5% reduction over the mediastinum and a 62% reduction over the lateral lung field compared with routine nonfilter examinations. The filter is inexpensive and readily adapted to any x-ray unit and is, therefore, an attractive alternative to costly high kVp sources. Furthermore, the attenuation coefficient for calcium in bone and parenchyma remains relatively high with preservation of calcium contrast. Repeat exposures have been minimized and the need for additional projections virtually eliminated.

Humans↗
PubMed1977

Fibrous mediastinitis: a late manifestation of mediastinal histoplasmosis.

Fibrosing mediastinitis is an uncommon manifestation of histoplasmosis that occurs primarily in younger patients. Findings include tracheobronchial narrowing, compromise of the main pulmonary artery and veins, and circumferential narrowing of the esophagus. The initial chest radiograph is often diagnostic, although additional studies including tomography and angiography help clarify the extent and severity of the disease process.

Adolescent↗
PubMed1975

Displacement of pontine arteries by fungating pontine astrocytomas.

Pontine astrocytomas may fungate, encircling the basilar artery and pontomesencephalic vein and intruding between these structures and the clivus. The tumor thus may prevent anterior displacement of these vascular structures against the clivus or produce paradoxical posterior displacement. However, the pontine arteries are usually swept forward by the tumor nodules to lie anterior to the basilar artery. These arteries are also stretched as they encircle the enlarged pons, losing their normal undulations. An increased posterior extent of the vessels may be seen, presumed due to hypertrophy or displacement or both. These findings seem highly specific for the diagnosis of fungating pontine astrocytoma.

Age Factors↗
PubMedDate not supplied

Custom shade guide system for composite resins.

Shade guides that are included in most composite kits are not made of the actual resin material. Therefore the true shade, translucency, or opacity of the composite resin is not readily apparent with stock shade guides. Due to this fact, it has become evident that the best solution to the shade guide problem is to construct a custom shade guide from the actual resin. Until recently, fabrication of custom shade guides has been a time-consuming, inefficient task. Now, a simple and efficient method of forming accurate shade guides for composites is available. With its unique handle/template design, T-TABs enable a dentist to create a precise, labeled shade guide within minutes. There are many advantages to both dentist and patient when T-TABs are employed in the construction of custom shade guides.

Color↗