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Biomedical subjects

G Meyer

Publications and source records attributed to G Meyer.

At least 469 records · Page 26Linked to original sources
PubMed1977

Inability of naloxone to change brain morphine levels in tolerant mice.

The effect of naloxone on brain morphine concentrations was measured in naive and morphine-dependent mice using radioimmunoassay and gas-liquid chromatography. No displacement of morphine from the brain by naloxone could be observed in naive mice acutely injected with morphine or in pellet-implanted mice at increasing intervals after removal of the morphine pellets. The suggestion of a change in affinity of opiate receptors during the development of tolerance/dependence, which had been made on the basis of the displacement of morphine by naloxone found by other workers, is thus not supported by the present results.

Animals↗
PubMed1977

[Role of acoustic stress on the development of polyoma tumors in immunized golden hamsters].

An acoustic stress increases the metastatic spread of polyoma virus-induced tumors in syrian Hamsters. To try to elucidate the mechanism of this action, we studied the effect of stress on the protection afforded by the virus against tumour challenge. Exposure to ultrasonics during the immunization period markedly decreased the protective effect of the virus.

Acoustic Stimulation↗
PubMed1977

Electrical parameters in gallbladders of different species. Their contribution to the origin of the transmural potential difference.

Amphotericin B enhances Na+ conductance of the mucosal membrane of gallbladder epithelial cells and in such a way it modifies the brush border electromotive force. On this basis a method to measure cell and shunt resistances by comparing changes of the mucosal membrane potential (Vm) and of the transmural p.d. (Vms) is developed. This method is applied in gallbladders of different vertebrate species (i.e. rabbit, guinea pig, goose, tortoise, toad, trout). The two tested mammals, rabbit and guinea pig, exhibited a lower shunting percentage (89--93%) than the nonmammals (96--97%), but this fact did not bring about a homogeneous positive Vms. This means that shunting percent contributes, but it is not the only source of differences in Vms, in accordance with that reported by Gelarden and Rose (J. Membrane Biol. 19:37, 1974). Moreover, mammals exhibited a lower luminal resistance and a lower ratio between luminal and basolateral resistance than nonmammals. Possible causes of these differences are discussed.

Amphotericin B↗
PubMed1977

Isolation of polyoma virus-induced surface antigens in hamster cells: potassium chloride solubilization and differential precipitation.

Surface antigens were extracted in soluble and active form with 3 M KCL from polyoma virus-transformed and embryonic hamster cells. These were tumor-specific transplantation antigens (TSTA), shown by tumor rejection, and a surface (S) antigen, demonstrated by the inhibition of surface fluorescence on living polyoma virus-transformed cells. The extracts were fractionated by salting out with ammonium sulfate. In tumor cell extracts, all TSTA activity and a part of S antigen activity were found in the fraction precipitated with 60% saturation in (NH/)2SO4. Another part of S antigen activity was found in the fraction precipitating at 80% saturation in tumor cell extracts. The precipitate at 60% saturation of embryonic cell extracts also had a part of S antigen activity. Receptor site activity for concanavalin A was also retained after solubilization and was confined to the 40% saturation (NH4)2SO4 precipitate in the case of tumor and embryonic cell extracts.

Animals↗
PubMed1977

A surface antigen associated with Hodgkin's disease: brief communication.

We used an indirect immunofluorescence technique to detect a surface antigen that may be associated with Hodgkin's disease (HD). A heteroantiserum raised in a rabbit given an injection of cells obtained from an HD lymph node (Stage I, classification of Lukes and Butler) allowed us to detect an antigen on the surfaces of HD-derived cells in 25 of 27 instances. Benign and malignant non-HD-type lesions (both lymph node and spleen) did not have this antigen. The nature of this antigen and the type of cells bearing it are unknown.

Antigens, Neoplasm↗
PubMed1977

The use of hybrid cells in immunotherapy.

HARRIS et. al. isolated somatic hybrid cells (A9/SEWA) between polyoma-induced tumor and mouse fibroblast cell lines. Although these hybrid cells were no longer tumorigenic, we found that their immunogenicity was conserved. It therefore seemed to us that these antigenic, non transplantable, living cells would be an ideal tool for immunotherapy experiments. In our first experiments we assessed the immunoprotection afforded by A9/SEWA cells in both the SEWA tumor/A.SW mouse and C3HPy/C3H mouse systems. However, the efficiency of immunization with hybrid cells is dependent on the stability of the cells, especially in respect to the expression of the TATA. So we also tried to evaluate the immunogenicity as a function of the number of subcultures undergone by the hybrid line. In both systems, the immunogenicity was very good in the early subcultures but, in the C3HPy tumor/C3H mouse system, a loss of immunogenicity was observed as the number of subcultures increased. Thus any clinical application or immunization by hybrid cells would necessitate the verification of the presence of the tumor-associated antigens at each subculture. We are at present experimenting with various in vitro techniques for detection of the expression of these antigens.

Animals↗
PubMed1977

[Different sensitivities to ultraviolet rays of various functions of the polyoma virus. Stimulation of the synthesis of cellular DNA].

Peritoneal Mouse macrophage were used to study the stimulation of cell DNA synthesis by polyoma virus. Using ultraviolet-irradiated polyoma virus, it was possible to show a difference between the inactivations of infectivity and of induction of DNA synthesis. By statistically analysis of these two phenomena it was found that 39% of the viral genome is necessary for the induction of cell DNA synthesis.

DNA↗
PubMed1977

[Detoxification of staphylococcal-enterotoxin B in water (author's transl)].

Staphylococcal enterotoxin B contaminated water has been detoxified with calcium hypochlorite used in the water treatment procedure which is available now in order to get drinking water from surface water in emergency cases. Changes in toxin-activity were measured serologically by agar-gel-immuno-precipitation as well as biologically by the "monkey-feeding test" with young macaca mulatta. With an initial concentration of 50 ppm chlorine in tap water resp. 200 ppm in native surface water concentrations of toxin up to 40 fold average emetic dose of rhesus monkey could be inactivated safely. It was pointed out an obvious conformity between precipitation test and monkey-feeding test. The clinical efficiency of SEB on rhesus monkeys has been investigated and discussed subsequently.

Animals↗
PubMed1976

[Immunologic blood-brain barrier in the polyoma virus--Syrian hamster system].

The authors report premilinary results of an experiment on permeability of the blood-brain barrier (BBB) to anti-tumor virus-induced immunological factors in the polyoma virus/Syrian Hamster system. The animals were protected by subcutaneous or intracranial injections with virus before challenge with polyoma virus transformed cells by both routes. BBB seemed to be permeable to the efferent part of the subcutaneously induced immune reaction. On the contrary, antigenic information introduced in the central nervous system was trapped inside the BBB. Thus the BBB might offer a "one-way" permeability in this system.

Animals↗