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R Schmidt-Ullrich

Publications and source records attributed to R Schmidt-Ullrich.

89 records · Page 5Linked to original sources
PubMed1976

Concanavalin A stimulation modifies the lipid and protein structure or rabbit thymocyte plasma membranes. A laser raman study.

(1) We have compared the laser Raman spectra of isolated plasma membranes from resting rabbit thymocytes and cells mitogenically stimulated with concanavalin A. (2) Major alterations in the CH stretching, CH deformation and CC stretching regions indicate a different lipid architecture in the membranes from activated cells. (3) Spectral changes in the Amide I and II regions, by reference to the spectra of model compounds indicate greater protein amidation in the membranes from stimulated cells.

Animals↗
PubMed1976

Low- and high-affinity concanavalin a binding to thymocyte plasma membrane vesicles.

Binding of concanavalin A to isolated thymocyte membrane vesicles occurs through (a) numerous (approximately 6 x 106/cell equivalent) low-affinity sites (Ka = 1.3 x 105M-1) anf (b) fewer (approximately 0.4 x 106/cell equipment) specific receptors (Ka = 6.8 x 106 M-1) defined as 55,000 D glycoprotein and its multimers. Specific binding is positively-cooperative, with a Hill coefficient of approximately 1.8. Low concentrations of glutaraldehyde selectively crosslink the 55,000 D glycoprotein with replacement of positively-cooperative sites by high-affinity sites. It is proposed that concavalin A-binding induces multimerization of the 55,000 D glycoprotein.

Animals↗
PubMed1976

Cooperative binding of concanavalin A to thymocyte membrane vesicles augments uptake of alpha aminoisobutyrate.

(1) Membrane vesicles from rabbit thymocytes accumulate alpha-aminoisobutyrate in the presence of 0.1 M NaCl. Uptake is 1/2 maximal after about 2 min and reaches a plateau value (61 pmoles/mg protein) after 30 min. (2) Up to 25 mug concanavalin A/ml, binding of the lectin describes a sigmoid curve indicative of a cooperative process. (3) At lectin concentrations up to 8 mug/ml, lectin binding enhances the uptake of alpha-aminoisobutyrate (maximally 30%).

Aminoisobutyric Acids↗
PubMed1976

Membranes of normal hamster lymphocytes and lymphoid cells neoplastically transformed by simian virus 40. I. High-yield purification of plasma membrane fragments.

In this first paper of a series comparing the membranes of normal lymphocyte populations from male outbred Syrian hamsters with those of neoplastic transformants (GD 248) induced by simian virus 40, a method is described for the isolation of representative plasma membrane (PM) fragments from both cell types. Multiple criteria were used to monitor the purity and yield of PM material after cell disruption by nitrogen cavitation and after membrane fractionation by a combination of differential centrifugation and isopyknic ultracentrifugation in dextran density gradients. Lactoperoxidase-catalyzed radioiodination before cell disruption was used as an extrinsic surface marker; Na+,K+-activated ATPase, as well as alkaline phosphatase, was used as intrinsic functional PM markers. The distribution of nuclei, mitochondria, lysosomes, and endoplasmic reticulum (ER) during fractionation was monitored by the measurement of DNA, succinate dehydrogenase and monoamine oxidase, beta-glucuronidase and glucose-6-phosphatase, and NADH:lipoamide oxidoreductase, respectively. According to the three PM markers employed, a 15- to 20-fold purification (over homogenate) and a PM yield of about 65% were obtained for both cell categories, with negligible contamination by DNA, mitochondria, lysosomes, and er. The procedure also allowed recovery of 60% of the mitochondria free of other cell elements.

Adenosine Triphosphatases↗
PubMed1976

Membranes of normal hamster lymphocytes and lymphoid cells neoplastically transformed by simian virus 40. II. Plasma membrane proteins analyzed by dodecyl sulfate-polyacrylamide gel electrophoresis and two-dimensional immune electrophoresis.

The plasma membrane proteins of lymphocyte populations from normal outbred Syrian hamsters were compared with those of a neoplastic transformant line (GD 248) induced by simian virus 40. Both quantitative and qualitative differences were observed. Gradient dodecyl sulfate-polyacrylamide gel electrophoresis revealed 12 major protein components in the membranes of both cell populations. Both membrane categories also contained small amounts of immunoglobulin. Compared with the membranes of the reference cell population, GD 248 membranes showed a 60% decrease of approximately 210,000 daltons of glycoprotein; a 10% reduction of about a 48,000-dalton band and virtually complete loss of a 15,000-dalton component concomitant with a 57% increase in a 52,000-dalton band; fusion to two subcomponents (mol wt approximately 250,000 daltons); and emergence of approximately 120,000 and 30,000 daltons glycoproteins. In addition, the relative mobility of an approximately 95,000-dalton component increased by roughly 0.02 U. Crossed immune electrophoresis in Trition X-100 with heterologous antiserum against GD 248 microsomal membranes revealed both a new component with a high level of electrophoretic mobility and intensification and additional heterogeneity in a strongly antigenic component with a low level of electrophoretic mobility. Crossed-line immune electrophoresis indicated that at least two antigens in the membranes of GD 248 cells lacked the membranes of the reference cell population.

Animals↗
PubMed1975

The structure and thermotropism of thymocyte plasma membranes as revealed by laser-raman spectroscopy.

1. Plasma membranes from rabbit thymocytes have been analyzed by laser-Raman spectroscopy over the 800-3000 cm-1 region and the spectra compared with those of endoplasmic reticulum, as well as relevant liposome systems. 2. Evaluation of the Amide I and Amide III regions indicates that thymocyte plasma membranes, but not endoplasmic reticulum, contain appreciable beta-structure peptide. This conclusion is supported by infrared spectroscopy. 3. Evaluation of the 2890 cm-1: 2850 cm-1 intensity ratio of plasma membranes as a function of temperature, using an integration technique, demonstrates a thermotropic lipid transition centered near 23 degrees C. This transition is less sharp than one observed with egg lecithin in this temperature range. 4. The significance of the thermotropic transition is evaluated in view of the lack of thermotropic lipid-protein segregation detectable by freeze-fracture electron microscopy (Wunderlich, F., Wallach, D.F.H., Speth, V. and Fischer, H. (1973) Biochim. Biophys. Acta 373, 34-43).

Animals↗
PubMed1975

Concanavalin A-reactive protein of rabbit thymocyte plasma membranes: analysis by crossed immune electrophoresis and sodium dodecylsulfate/polyacrylamide gel electrophoresis.

1. Thymocyte plasma membrane extracts, prepared with the non-ionic detergent Triton X-100, show 10 major protein components upon sodium dodecysulfate/polyacrylamide gel electrophoresis and at least 11 immunologic components upon crossed immune electrophoresis. 2. Concanavalin A reactive membrane proteins have been identified using crossed immune electrophoresis with receptor-ligand interaction. 3. These proteins are absorbed from Triton X-100-solubilized membranes onto immobilized concanavalin A. They are eluted in stepwise fashion, using increasing concentrations of alpha-methyl-d-glucoside, between 0.0004 M and 0.1 M. The predominant proteins eluted in each step are components with high electrophoretic mobility in crossed immune electrophoresis and are identical with a glycosylated component in sodium dodecysulfate/polyacrylamide gel electrophoresis with molecular weight of 55 000. 4. This component forms multimers in the presence of Triton X-100 which are not totally dissociated in sodium dodecylsulfate. 5. Neuramidase treatment followed by crossed immune electrophoresis of total plasma membrane isolates, as well as the purified glycoprotein fraction, indicates that the concanavalin A-reactive proteins are sialoglycoproteins. 6. Sodium dodecylsulfate component 5.1 comprises at least two different populations of glycoproteins (6 and 9) in crossed immune electrophoresis, one of which exclusively exhibits heterogenous carbohydrate antigenic sites (component 9). 7. Present data, taken together with previously published experiments, indicate that concanavalin A binding to intact thymocytes induces an increased turnover and release of the receptor protein(s).

Animals↗
PubMed1975

Ultrastructural localization of in vivo bound immunoglobulins in bullous pemphigoid--a preliminary report.

The ultrastructural location of in vivo bound immunoglobulins in a case of bullous pemphigoid was determined by coupling peroxidase to antihuman gamma globulin. Immunoglobulin deposits were found exclusively in the space between the basal cells and the basal lamina. The location of the immunoglobulin in bullous pemphigoid thus differs from that in lupus erythematosus where immunoglobulins are found mainly below the basal lamina.

Antibodies, Anti-Idiotypic↗
PubMedDate not supplied

High-dose boost irradiation techniques for carcinoma of the nasopharynx.

Irregularly shaped tumors of the nasopharynx require the capacity to design flexible and reproducible treatment plans for high-dose boost irradiation. We use a variety of external beam techniques which may be combined with an afterloading intracavitary implant. Careful planning of such treatment is crucial and requires an accurate assessment of tumor volume and regional anatomy as defined by lateral simulator films, computed tomography, and magnetic resonance imaging scans. External beam irradiation is performed using a variety of arc rotations or fixed-beam cross-fire techniques in order to maximize the dose to an irregular tumor volume while minimizing irradiation of sensitive neighboring structures. Intracavitary implantation is achieved by constructing a mold of the nasopharynx with a silastic polymer and fitting it with hollow plastic catheters for afterloading with iridium-192.

Brachytherapy↗