Molecular magnesium hydrides supported by an anionic triazacyclononane-type ligand.

Molecular magnesium hydride with a terminal metal-hydrogen bond [Mg(iPr2TACN·AliBu3)H]2 supported by a monoanionic TACN-type ligand (TACN = 1,4-di-isopropyl-1,4,7-triazacyclononane) rearranges to form the dinuclear magnesium hydride [Mg(iPr2TACN·AlHiBu2)(µ-H)]2, exhibiting a rare MgH-Al interaction.

Histamine release from rat mast cells induced by the lectin from the snail, Cepaea nemoralis L. - a counterpart to the triggering action of polycations?

One of the two lectins, occurring in the albumen gland of the snail, Cepaea nemoralis L., is shown to be a histamine releaser from isolated rat mast cells as well as in vivo. The release reaction is induced in the same dosage range as the agglutination of human red blood cells occurs. Both the reactions are inhibitable by the addition of N-acetyl-neuraminic acid. The releasing activity of the lectin seems to be a counterpart to the triggering action of polycations, because its specificity is directed against this sugar.

[Serological studies of cestode cysts. P1 blood-group activity in cysts of zoo animals]. / Serologische Untersuchungen an Zestodenzysten. P1-Blutgruppenaktivität in Zysten von Zootieren

The cyst fluid of cestodes from various animals kept in zoological gardens was examined for the presence of A-, B-, H- and P1-blood group activity. While the results in the ABH-system were negative, the cysts from 2 of 13 animals examined (1 elk and 1 reindeer) presented P1-blood group activity.

[Immunostimulation by 2-cyanoethylurea: accelerated rejection of skin allografts in mice]. / Immunstimulation durch 2-Cyanoethylharnstoff: Beschleunigte Abstossung allogener Hauttransplantate bei der Maus.

2-Cyanoethylurea (2; CEU or BA 1-4) obtainable from 1-carboxamido-2-cyanoaziridine (2; BA l) by ring fission possesses immunomodulating properties like its parent compound containing the intact aziridine ring, as well as other 2-cyanoaziridine (1) derivatives. As was shown in a mouse model, CEU accelerated the time of rejection of skin allografts (immunostimulation) and reduced the prolonged tolerance time of mice immunosuppressed with cyclophosphamide to values found in normal control animals (immunorestoration).

Mast cells and complement activating immune reactions.

A rosetting of isolated rat mast cells with complement coated zymosan does not induce a histamine release. However, this procedure potentiated the release induced by ATP. Treatment of rats with prednisolone diminishes the number of the rosette forming mast cells.

The role of N-acetyl-neuraminic acid in the triggering of rat mast cells by polycationic molecules.

Three substances known to act on N-acetylneuraminic acid (NANA), were tested for their activity on rat peritoneal mast cells. Both neuraminidase, which splits off NANA, and the lectin from Cepaea nemoralis directed against NANA are histamine releasers. Periodate itself did not trigger the cells but inhibited the releasing action of other substances. The results provide further evidence for the role of NANA in the triggering of mast cells. A cytotoxic substance, benzyl-polyethylene imine, triggers mast cells without affecting NANA. In addition, the role of histamine-BSA conjugates as histamine releasers is described.

Histamine release from rat mast cells induced by protamine sulfate and polyethylene imine.

The protamine sulfate-induced release of histamine from mast cells in a non-cytotoxic reaction, similar to the 48/80-induced secretion. Polyethylene imine was found to be a less potent releaser. It is a cytotoxic substance without specificity for mast cells and acts on membranes generally. Although the two agents are related concerning their molecular weight and polybasicity, their mode of action on mast cells is clearly different.

Histamine and immune reactions. 3. Inhibition of early events of human lymphocyte activation by histamine.

Histamine inhibits the chemiluminescence response of human lymphocytes to Concanavalin A by interfering with early triggering events. The inhibition seems to be mediated via H2 receptors, acts immediately, and is reversible by washing. A longer incubation in a histamine-containing medium induces a refractory state of the cells. The inhibitory effect described here is compared with the inhibitory action of histamine in the lymphocyte transformation test.

[Manufacture and possibilities of use of antisera against solubilized human erythrocyte membranes]. / Erzeugung und Anwendungsmöglichkeiten von Antiseren gegen solubilisierte menschliche Erythrozytenmembranen

Antisera produced in rabbits against Triton X-100 solubilized human erythrocyte ghosts formed several several precipitation lines in immunoelectrophoresis and immunodiffusion tests against the solubilized ghosts. The antisera were used for detecting several membrane components during chromatographic separation. A membrane component was partially isolated using gel filtration on SEPHADEX G-200 (fraction F1/F2). Spectrin (Tektin A) was shown to be the main moiety of these fractions. Associated proteins (haemoglobin, GAPD) could not be detected by the antisera against whole ghost solubilisate.

[Mode of action of protamine sulfate on histamine secretion in the rat mast cells]. / Zur Wirkungsweise von Protaminsulfat bei der Histaminsekretion aus Rattenmastzellen.

Protamine sulfate, known for a long time as a histamine releaser, was labeled with a fluorescent dye (FITC). This conjugate was shown to stain selectively the mast cell fraction of rat peritoneal cells. Within a few seconds, the protamine was found inside the cells. Although the cells had lost their histamine completely, no granules were found outside the cells. In the electron microscope, the protamine treated mast cells showed a loss of the electron density of their granules, a vacuolization, and other signs of histamine release. Evidence for a direct connection between the vacuoles and the extracellular fluid was gained by incubating mast cells in FITC-labeled human serum albumin followed by the addition of unlabeled protamine. After washing, the fluorescence was found to be located inside the cells, demonstrating an influx of the FITC-HSA under the influence of protamine. The protamine-induced release reaction is increased after addition of Ca2+, reduced by lowering the temperature, addition of 2-deoxyglucose, or cytochalasin B. Disodium cromoglycate also diminished the histamine release in a dose dependent manner. Protamine did not induce a loss of lactate dehydrogenase from the mast cells. The release reaction is mediated by the cell membrane, as shown by the releasing activity of insolubilized protamine. We conclude that the protamine-induced release is a non-cytotoxic reaction, fulfilling some criteria of the anaphylactic histamine release.

[Histamine liberation from rat mast cells by culture supernatants of human lymphocytes and rat spleen lymphocytes]. / Histaminfreisetzung aus Rattenmastzellen, hervorgerufen durch Kulturüberstände menschlicher Lymphozyten und von Rattenmilzlymphozyten.

The supernatant of mitogen- or antigen-stimulated mononuclear cell cultures is known to contain a large number of biologically active molecules. In the present study, we have stimulated human mononuclear cells and rat spleen cells with Con A or antigen (PPD) respectively to produce lymphokines, such as histamine releasing factor (HRF), which is capable of causing histamine release from rat mast cells and human basophils. Histamine was measured fluorimetrically by Shore et al. This assay is sensitive and reproducible: replicates varied by less than 15% in triplicate samples.

[Supression of angiotensin II-induced contraction of the isolated guinea pig ileum by alveolar surfactants (author's transl)]. / Uterdrückung der angiotensin II-Kontraktion am isolierten Meerschweinchen-Ileum durch perbronchial ausgespültes oberflächenaktives Material aus der Lunge.

The guinea pig alveolar surfactant reduces the contraction of the isolated guinea pig ileum, induced by Angiotensin II. It is tentatively proposed, that the surfactant system suppresses the reactivity of lung blood vessels towards contacting stimuli.

Anti-A agglutinin from Helix pomatia as a marker for L cells.

By means of fluorescein-labeled anti-AHP agglutinin isolated from the albumen gland of the snail Helix pomatia L. L cells were detected in air dried and fixed monolayer preparations, smear preparations or cryostat sections of tumours induced in two different host systems. The tumours consisting of L cells could be clearly distinguished from the surrounding normal host tissues, and also single tumour cells lying separtely in the host tissued were identified in the same unequivocal manner. The cells were marked by characteristic granular fluorescence caused by specific agglutinin binding within the cell membrane. With these results the previously expressed thesis that anti-AHP agglutinin might be used as a marker for L cells is confirmed for L cells grown in suitable host systems, too.

[Receptors for complement on rat mast cells and release of histamine]. / Komplementrezeptoren auf Rattenmastzellen und Histaminfreisetzung.

Using rat complement-treated zymosan particles a rosetting of purified rat peritoneal mast cells could be demonstrated. The question was investigated whether the binding of activated complement could be a trigger of histamine release. Varying the degree of complement label on the zymosan particles, the time and temperature of incubation and the dependence on Ca2+ ions, we could not induce a release of histamine in any case. The addition of labeled zymosan increased slightly the mediator release induced by ATP. The immunologic significance of the complement receptors on mast cells is still unclear.

Fluorescence microscopical visualization of rat mast cells by means of fluoresceine isothiocyanate labeled protamine sulfate.

Using fluoresceine isothiocyanate labeled protamine sulfate it is possible to stain rat mast cell fractions of isolated periotoneal cells in a selective way. The cells are not degranulated, though they have lost their histamine completely. The method shows the dissociation of the mediator release and the extrusion of the granules.

[Serological identification of spectrin in the 2 dimensional immunoelectrophoresis]. / Serologische Identifizierung von Spektrin in der zweidimensionalen Immunoelektrophorese

Using polyvalent antisera directed against solubilized human erythrocyte ghosts in the immunoelectrophoresis we obtained some precipitation arcs. Antisera against the purified spectrin allowed the identification of spectrin in the crossed immunoelectrophoresis.

[Histamine and immune reactions. 1. Histamine receptor-bearing lymphocytes]. / Histamin und Immunreaktionen. 1. Histaminrezeptor-tragende Lymphozyten.

Literature review. Mast cells and basophils are included not only in anaphylactic but also in complement activating and cell-mediated immune reactions. A histamine release can be induced via the IgE mechanism, the anaphylatoxins, the histamine releasing activity, and by other reactions. Histamine and several other mediators induce a local inflammation reaction either by a direct action on their target cells or indirectly by the activation of other humoral and/or cellular effector systems. Histamine influences several immune reactions. Here, its influence on histamine receptor-bearing lymphocytes is discussed more in detail. Using in vitro test systems, it has been shown that histamine has a dual effect, it induces a suppression when applied in higher concentrations, while low concentrations are stimulating. In vivo, histamine receptor-bearing lymphocytes have suppressive functions, mediated by H2 receptors. Some preliminary evidence for the inclusion on histamine in the immunoreagulation of patients with several diseases is presented.