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Biomedical subjects

G Schwarzmann

Publications and source records attributed to G Schwarzmann.

61 records · Page 4Linked to original sources
PubMed1979

Sialic-acid content of low-density lipoproteins controls their binding and uptake by cultured cells.

The (high-affinity receptor)-mediated uptake of homologous low-density (low-rho) lipoproteins by cultured human arterial smooth muscle cells or human skin fibroblasts is controlled by the sialic acid content of low-rho lipoprotein particles. This conclusion is derived from the following results. 1. Gangliosides incubated with native low-rho lipoproteins associate with low-rho lipoprotein particles. Low-rho lipoproteins modified by associated GLac1, GGtet1, and GGtet2b + GGtet3 gangliosides are internalized by arterial smooth muscle cells at a rate up to 80% lower than native low-rho lipoproteins or those preincubated with desialized gangliosides. 2. The inhibitory effect of gangliosides is specific for high affinity uptake and not detectable on skin fibroblasts deficient in low-rho-lipoprotein receptor. 3. Desialyzed low-rho lipoproteins are internalized by smooth muscle cells up to 100% faster than native low-rho lipoproteins, the enhancement of uptake corresponding to the degree of desialization.

Aorta↗
PubMed1978

A simple and novel method for tritium labeling of gangliosides and other sphingolipids.

A very simple method for introducing tritium specifically into the ceramide portion of gangliosides, neutral glycosphingolipids and sphingomyelin has been developed using potassium boro [3H]hydride and palladium as catalyst. In this way six different gangliosides, five different neutral glycosphingolipids and sphinomyelin with high specific radioactivity were prepared for the first time. This simple procedure which does not require sophisticated apparatuses is suitable for large scale preparation of tritium-labeled sphingolipids as well as for nanogram quantities of individual sphingolipids so as to serve for analytical purposes. During the course of the labeling procedure no degradation of even the most labile trisialosyl-gangliotetraosylceramide has been observed. The yield of tritiated compounds is almost quantitative. The specific radioactivity depends on the unsaturation of the ceramide moiety and the specific activity of the boro[3H]hydride employed.

Autoradiography↗
PubMed1978

Studies of ligand binding to cholera toxin, III. Cooperativity of oligosaccharide binding.

Binding parameters for the interaction of cholera toxin and choleragenoid with monosialo-gangliotetraose, the oligosaccharide moiety of ganglioside II3 NeuAc-GgOse4-Cer, have been measured by equilibrium displacement dialysis. The experimental data were evaluated by a curve fitting computer program. The binding curves obtained at 6 degrees C reflected positive cooperativity with average Hill coefficients in the range of 1.16 to 1.25. The cholera toxin as well as its ganglioside-binding protomer B-protein bind 4 mol of monosialogangliotetraitol per mol of protein. The presence of disulfide-cleaving agents like 2-mercaptoethanol did not eliminate the cooperativity of the binding characteristics, but increased the Hill coefficient.

Cholera Toxin↗
PubMed1978

Comparison of the interaction of mono- and oligovalent ligands with cholera toxin. Demonstration of aggregate formation at low ligand concentrations.

The stimulation by cholera toxin of adenylate cyclase in Chinese hamster ovarian cells could be inhibited by various ligands. The latter have been shown to contain the structural oligosaccharide entities required for binding to cholera toxin, established as Galbeta1 leads to 3GalNAcbeta1 leads to 4Gal3 comes from 2alphaNeuAc. The different inhibitory potency of the ligands thereby correlates with the size of the aggregates formed with the toxin, which in turn depends on the valency of the ligands. The conclusion is drawn from a comparison of the interaction of cholera toxin and its B-protomer with ganglioside II3NeuAc-GgOse4-Cer, the newly synthesized bis-(monosialo-gangliotetraityl)amine and monosialogangliotetraose. In a double diffusion test cholera toxin B-protomer precipitated with the ganglioside II3 NeuAcGgOSE4-Cer and the divalent ligand bis(monosialo-gangliotetraityl)amine, suggesting the formation of high molecular weight aggregates, whereas no precipitation was observed with the monovalent monosialo-gangliotetraose. By ultracentrifugation analysis, aggregate formation of the cholera toxin B-protomer could be demonstrated with the ganglioside II3 NeuAc-GgOse4-Cer and bis(monosialo-gangliotetraityl)amine at a concentration at which the ganglioside was assumed to be monodisperse. Ganglioside/cholera toxin B-protomer complexes sediment faster than those of the toxin and bis(monosialo-gangliotetraityl)amine, suggesting higher aggregation of cholera toxin B-protomer with the former. On the other hand, no sedimentation with monosialo-gangliotetraose was observed. By equilibrium displacement dialysis, however, a comparable high affinity of binding to cholera toxin B-protomer of both the mono- and divalent oligosaccharides was demonstrated. Furthermore, values for the maximal concentration of the bound ligand from these binding experiments with cholera toxin B-protomer established molar ratios of ligand to protein of 4 to 1 and 2 to 1 for monosialo-gangliotetraose and bis(monosialo-gangliotetraityl)amine, respectively. From the results it is concluded that the lipophilic moiety of the ganglioside is not directly involved in the binding process to the toxin protein but leads to an oligovalency of this ligand, due to formation of micellar or submicellar structures.

Adenylyl Cyclases↗
PubMed1977

Studies of the ligand binding to cholera toxin, II. The hydrophilic moiety of sialoglycolipids.

The binding between cholera toxin or its B-protein subunit and various ganglioside-related oligosaccharides was studied by equilibrium displacement dialysis. At low concentrations of ligand, the binding of monosialo-gangliotetraitol exceeded that of the parent ganglioside II3NeuAcGgOse4-Cer, the possible cell surface receptor for the toxin. The terminal galactose residue and an intact carboxyl group of the sialic acid moiety of monosialo-gangliotetraose were found to be necessary for strong binding to the toxin.

Chemical Phenomena↗
PubMedDate not supplied

[Clinical aspects and therapy of amniotic fluid embolism. Illustration based on a case report].

A case of amniotic fluid embolism during the delivery of an at term pregnancy is reported. The 34-year old primipara with an unremarkable medical history suddenly suffered from a seizure in the second stage of labor. Shortly prior to this event, a prolonged fetal bradycardia was recorded. After forceps delivery a massive postpartum haemorrhage as the result of a consumption coagulopathy occurred. Immediate resuscitation with artificial ventilation improved the condition of mother and child. The substitution of packed red cells and platelets, fresh frozen plasma and other blood derivates was necessary. Mother and child survived without any physical damage or neurological deficit. Because of the clinical pattern we diagnosed an amniotic fluid embolism.

Adult↗