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Biomedical subjects

G Erdmann

Publications and source records attributed to G Erdmann.

At least 19 recordsLinked to original sources
PubMed1992

Isotype-specific rabbit antibodies against chinchilla immunoglobulins G, M, and A.

Chinchillas have become a preferred animal model for studying otitis media, and are also useful in studying insulin release, gastrin physiology, intestinal infection, and hepatocellular pathophysiology. Immunopathologic studies in the model, however, have been limited by absence of specific antibody reagents against chinchilla immunoglobulins. We describe a method for preparing isotype-specific rabbit antibodies against the heavy-chain components of chinchilla immunoglobulins G, M, and A. Chromatographic techniques were used to isolate chinchilla immunoglobulins from serum and breast milk; heavy-chain fractions were isolated and used as antigens to produce isotype-specific antibodies in New Zealand White rabbits. Enzyme-linked immunosorbent assay of these antisera disclosed anti-light chain cross-reactivity, which was removed by affinity chromatography. The isolation and affinity purification techniques were highly reproducible. The availability of these reagents should greatly enhance the utility of the chinchilla in modeling human disease.

Animals↗
PubMed1991

Uptake and concentration of bioactive macromolecules by K562 cells via the transferrin cycle utilizing an acid-labile transferrin conjugate.

The transferrin cycle was used to attempt the import of bioactive macromolecules into cells with the aid of an acid-labile cross-linking agent. Anti-tetanus F(ab')2 fragments were iodinated and then conjugated to transferrin with a newly developed acid-labile cleavable cross-linking reagent, bismaleimidoethoxy propane, following thiolation of both proteins. Noncleavable conjugates were also prepared. At saturating conjugate concentrations, the uptake rate for both conjugates averaged over the first 2 h is about 6.5 fmol/million cells/min. Incubation of loaded cells in fresh medium for 30 min and analysis of cell pellets and supernatants reveal that 1) of the previously cell-associated label, only intact conjugate (about 50% of the label) is returned to the medium; 2) most of the remaining cell-associated material for the cleavable conjugate is chromatographically coincident with free Fab with some contribution from free F(ab')2 fragments. In contrast, the cell pellets loaded with noncleavable conjugates contained intact transferrin-F(ab'), conjugates. These results are consistent with transferrin receptor-mediated uptake of acid-labile conjugate followed by hydrolysis in acidified endosomes and resulting in concentration of free F(ab')2 and Fab within a prelysosomal intracellular compartment. A protein shuttle such as transferrin may therefore be used with ketal based acid-labile cross-linkers to load foreign molecules into an intracellular compartment. In addition, these data provide independent confirmation of the low pH compartment within the transferrin cycle. This new methodology is applicable to other cases of receptor/ligand trafficking to report low pH compartments independent of morphological analysis. Since transferrin receptors are overexpressed in tumors, antineoplastic agents could be targeted to tumors as transferrin acid-labile conjugates. This import system might be particularly useful in combatting the tumor cell export of antitumor agents occurring in multidrug resistance.

Cell Compartmentation↗
PubMed1991

The translocation of botulinum A neurotoxin by chromaffin cells is promoted in low ionic strength solution and is insensitive to trypsin.

Botulinum A neurotoxin (BoNtx) produced a partial inhibition of carbachol induced 3H-noradrenaline (3H-NA) release from bovine adrenal chromaffin cells in monolayer culture. Each of the polysialogangliosides GD1a, GT1b and GD1b enhanced the block of exocytosis when they were applied prior to the toxin exposure. The monosialoganglioside GM1 was not effective. Chromaffin cells treated with neuraminidase lost their sensitivity to BoNtx. Application of gangliosides to these cells, however, restored their susceptibility to the toxin. Treatment of the cells with trypsin did not affect the BoNtx-blockade of 3H-NA-release. The potency of botulinum A toxin was increased in a solution of low ionic strength in which sodium chloride was replaced by sucrose. In agreement with the potency of botulinum A neurotoxin in blocking exocytosis under the various conditions, binding of 125I-botulinum A neurotoxin to chromaffin cells was enhanced in low ionic strength solution and by pretreatment of the cells with gangliosides. The binding was decreased by digestion of gangliosides with neuraminidase. It is concluded that botulinum A neurotoxin binds exclusively to polysialogangliosides which subsequently serve as carriers for the toxin. The low ionic strength may increase some physico-chemical interaction of the toxin with the polysialogangliosides.

Animals↗
PubMed1990

Effects of cytokines on in vitro colony formation of primary human tumour specimens.

Although under study to alleviate chemotherapy-induced bone marrow toxicity, cytokines can stimulate in vitro growth of solid human tumour cell lines. The effects of granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor (G-CSF) and interleukin-3 (IL-3) on in vitro colony formation of primary human tumours was studied in a capillary soft-agar cloning system. Of 108 tumour specimens from 100 patients, 85 specimens were tested against all three factors at concentrations ranging from 0.1 to 1000 ng/ml. 44 of 100 tumours showed adequate growth in controls. 8 out of 43 (19%) specimens were significantly stimulated by GM-CSF, 6 of 40 (15%) by G-CSF and 10 of 44 (23%) by IL-3. Sensitivity to all three cytokines was observed in 4 of 44 (9%) specimens. By light microscopy the appearance of colonies from stimulated specimens was identical to that of controls. Sensitivity to cytokines was independent from sensitivity to epidermal growth factor, transferrin or insulin. Sensitivity to GM-CSF, G-CSF and IL-3 may be aberrantly expressed in a subgroup of solid human tumours.

Biopsy↗
PubMed1990

Uptake of antitetanus F(ab')2 fragments into eukaryotic cells.

1. In order to introduce antitetanus immunoglobulin fragments into eukaryotic cells, either antitetanus F(ab')2 or Fab' fragments have been linked to carrier molecules. Aciclovir, horseradish peroxidase, wheat germ agglutinin, and transferrin were tried as carriers. 2. F(ab')2-aciclovir and Fab'-horseradish peroxidase were not internalized by NG108-15 neurohybridoma cells. 3. [Fab']2-wheat germ agglutinin and F(ab')2-transferrin conjugates were internalized into various cells. 4. F(ab')2-transferrin conjugates were made with three different linkers: N-succinimidyl 3-(2-pyridyldithio) propionate, bis-maleimido hexane, and bis-maleimidoethoxy propane. All three conjugates were internalized but had a different fate inside the cells.

Acyclovir↗
PubMed1984

Liposome-entrapped [125I]anti-tetanus immunoglobulin G: evidence for entry into spinal cord neurons of the rat.

Intrathecally administered free anti-tetanus immunoglobulin G (IgG) diffuses through the spinal cord but does not enter nerve cells. In order to facilitate entry into neurons, 125I-labeled anti-tetanus IgG was entrapped in liposomes. After injection into the cerebrospinal fluid of rats, however, only a very low specific radioactivity of the spinal cord could be calculated from gross counts and no neuronal labeling was seen in autoradiographs. Therefore, it was assumed that the liposomes were unable to cross the basement membrane of the spinal cord surface. To circumvent this barrier the liposome-entrapped [125I]IgGs were injected directly into the grey matter. Histoautoradiographs then showed marked accumulations of radioactivity in neurons. Direct intraspinal injection of free [125I]IgG, on the other hand, failed to produce heavy neuronal labeling.

Animals↗
PubMed1984

Comparison of the emotional effects of a beta-adrenergic blocking agent and a tranquilizer under different situational conditions. I. Anxiety-arousing situations.

This study investigated the emotional effects of the beta-adrenergic blocking agent oxprenolol (40 mg, p.o.) and the tranquilizing agent diazepam (5 mg, p.o.) in healthy subjects under three situational conditions: an emotionally neutral control situation and two situations designed to arouse different levels of anxiety. Both oxprenolol and diazepam induced positive emotional changes only in the more strongly anxiety-arousing situation. Significant differences between oxprenolol and diazepam in inducing emotional stabilization were not demonstrable.

Adolescent↗
PubMed1983

Perfusion of the cervical spinal cord in situ of adult rats using a perfluorocarbon emulsion.

A method was developed for the perfusion of the cervical spinal cord of adult rats through the supplying arteries. A medium containing perfluorotributylamine as an oxygen carrier was used. The electrophysiological responsiveness was continuously monitored; pO2, pCO2, pH, Na+ and K+ were intermittently measured in the medium. The perfused cord maintained its responsiveness for more than 5 h. No changes in its structure became apparent in electron micrographs.

Animals↗
PubMed1981

[Atopic dermatitis in children (author's transl)].

Atopic dermatitis is a common chronic skin disorder in children of atopic constitution. There is a great variety of opinions regarding the possible causes, diagnostic measures and treatment of the disease. Important problems are skin testing, investigation of immunoglobulines E (RIST and RAST), food allergy in infants, elimination of allergens and hyposensitization. Symptomatic treatment often proves to be very effective, especially topical administration of corticosteroids. As a rule hospitalisation is not desirable. Sometimes, however, proper symptomatic treatment needs a lot of time and skill so that adequate nursing care in hospital is advisable. The mother can be instructed there, perhaps realizes prompt results and may obtain some rest after distressing situations at home.

Adrenal Cortex Hormones↗
PubMed1978

Interaction between physiological and cognitive determinants of emotions: experimental studies on Schachter's theory of emotions.

This study investigated the interaction between physiological arousal and situation-derived cognitions in the determination of feeling states that is proposed in Schachter's theory of emotions. The degree of bodily arousal was varied by disguised oral administration of a placebo or the sympathicomimetic agent ephedrine. The situational circumstances were varied by instructions offering cues for (a) no emotions ('neutral' control), or the feeling states called (b) 'anger', (c) 'happiness', and (d) anxiety'. The subjects were 72 male students. The dependent variables were blood pressure, heart rate, a list of bodily symptoms, and an adjective check list. The results within the 'anger' and 'happiness' condition were in accordance with Schachter's theory: depending on the type of situation, ephedrine-induced arousal either decreased or increased positive descriptions of mood. The emotional effects of the 'anxiety' condition, however, were independent of the drug-induced arousal level. Contrary to Schachter's theory, anxiety reactions occured also in a state of low physiological arousal and did not increase with increasing arousal.

Anger↗
PubMed1978

[Experimental study on the effect of ephedrine in an anger-provoking situation].

The purpose of this study was to investigate the effects of ephedrine-induced sympathetic arousal on emotional reactions in an anger-provoking situation. The effects of ephedrine were compared with a placebo condition while the effects of the anger-situation were compared to a neutral control situation. 60 male students were randomly assigned to one of the four conditions of the two-factor design. The dependent variables were various peripheral-physiological measures and self rating of physical and emotional states. Both independent variables were found to be effective. Contrary to expectation, ephedrine decreased subjective emotional reactions to the anger-provoking situation rather than increase it. Methodological problems and possible conclusions about the role of sympathetic arousal for emotional reactions are discussed.

Adult↗
PubMed1977

Histoautoradiography of central nervous system in rats with generalized tetanus due to 125I-toxin.

Rats were injected i.v. with 125I-tetanus toxin. In autoradiographs of the spinal cord radioactivity was found over the pericarya and in the surroundings of the motoneurones whereas grain density was less over their nuclear region. In addition, pericarya in the lateral horn of the thoracic region and also the bipolar cells of the spinal ganglia contained radioactivity. The central part and the dorsal horns of spinal cord, and the white substance did not show any appreciable radioactivity. Within the medulla oblongata, clusters of large cells representing motor nuclei, as well as some fibre tracts close to them, contained 125I. Forebrain and cerebellum remained free. According to its histoautoradiographic appearance, generalized tetanus can be described best as a combination of multiple local tetani.

Animals↗