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B Geiger

Publications and source records attributed to B Geiger.

176 records · Page 10Linked to original sources
PubMed1976

Low levels of beta hexosaminidase A in healthy individuals with apparent deficiency of this enzyme.

Appreciable beta hexosaminidase A (hex A) activity has been detected in cultured skin fibroblasts and melanoma tissue from healthy individuals previously reported as having deficiency of hex A activity indistinguishable from that of patients with Tay-Sachs disease (TSD). Identification and quantitation of hex A, amounting to 3.5%-6.9% of total beta hexosaminidase activity, has been obtained by cellulose acetate gel electrophoresis, DEAE-cellulose ion-exchange chromatography, radial immunodiffusion, and radioimmunoassay. Previous family studies suggested that these individuals may be compound heterozygotes for the common mutant TSD gene and a rare (allelic) mutant gene. Thus, the postulated rate mutant gene appears to code for the expression of low amounts of hex A. Heterozygotes for the rare mutant may be indistinguishable from heterozygotes for the common TSD mutant. However, direct visualization and quantitation of hex A by the methods described may prevent false-positive prenatal diagnosis of TSD in fetuses having the incomplete hex A deficiency of the type described in the four healthy individuals.

Cells, Cultured↗
PubMed1975

Specific determination of N-acetyl-beta-D-hexosaminidase isozymes A and B by radioimmunoassay and radial immunodiffusion.

The two major isozymes of N-acetylhexosaminidase, namely hexosaminidases A and B were quantitatively determined in tissues and biological fluids of both normal individuals and Tay-Sachs patients. The determination was carried out by two sensitive immunoassays:radial immunodiffusion, using chromogenic substrate, and radioimmunoassay, which were developed in this study. For this purpose [corrected] we used either a cross-reactive antiserum which reacts to a similar extent with both isozymes, or an antiserum reacting exclusively with hexosaminidase A (obtained by selective immunoadsorption). This enabled the quantitisation of the two isozymes separately, or in the presence of each other, in purified enzyme preparations or in tissue homogenates, affording a direct positive determination of hexosaminidase A. The results demonstrated that normal tissues contain the two isozymes in comparable amounts, whereas tissues of Tay-Sachs patients lack hexosaminidase A or any material which carries the A-specific antigenic determinants. The possible applications of these assays and their potential use in diagnosis are discussed.

Acetylglucosaminidase↗
PubMedDate not supplied

An alternative method of three-dimensional reconstruction from two-dimensional CT and MR data sets.

Cross-sectional images for medical diagnosis and therapy are obtained by sonography, CT or MRI. We propose an alternative solution to the problem of constructing a set of cross-sectional contours from two-dimensional (2D) CT or MR data sets. The method reduces the problem of constructing a shape over the cross-sections to one of constructing a sequence of partial shapes, each of them connecting two cross-sections lying on adjacent planes. The solution makes use of a spatial mathematical formalism (Delaunay triangulation). MR investigations were carried out on different objects (hips, livers) to illustrate the two-dimensional MR data sets by the reconstruction method. The resulting images represent the original image data in a way that is more suitable for observation of 3D relationships than the conventional cross-sectional viewing model.

Aorta↗
PubMedDate not supplied

Cell contact- and shape-dependent regulation of vinculin synthesis in cultured fibroblasts.

Recent studies have demonstrated the fundamental role of cell-substrate contacts and changes in cell shape in the regulation of cell growth, motility and differentiation, but the molecular basis for these phenomena is poorly understood. Because of the involvement of cytoskeletal networks in cell morphogenesis and contact formation, it is of interest that the expression of genes encoding several cytoskeletal proteins is markedly affected by changes in cell contacts and configuration. Because most of these phenomena involve changes in the form, extent or topology of cell contacts, we sought to determine whether the expression of components directly involved in the formation of cell-cell or cell-substrate contacts is affected by the respective cellular interactions. A suitable candidate for such analysis is vinculin, a cytoskeletal protein of relative molecular mass (Mr) 130,000 (130K), which is localized in focal contacts and intercellular adherens junctions. The assembly of vinculin into a membrane-bound junctional plaque seems to be one of the earliest cellular responses to contact with exogenous substrates, leading to the subsequent local assembly of the actin-rich microfilament bundles. Here we report on the regulation of vinculin synthesis in response to environmental conditions that affect cell shape and contacts.

Animals↗