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H Lentzen

Publications and source records attributed to H Lentzen.

40 records · Page 3Linked to original sources
PubMed1975

Uptake of dopamine into fractions of pig caudate nucleus homogenates.

Homogenates of the caudate nucleus of the pig were submitted to differential centrifugation. The 20000 g and 80000 g fractions were isolated and a part of them was osmotically shocked. The highest dopamine content per mg protein was found in the intact 80000 g fraction. Incubation experiments with the intact and the osmotically shocked fractions at 25 degrees C revealed that the particles of the intact 20000 g fraction took up dopamine, the influx of the amine was not enhanced by addition of ATP and magnesium to the incubation medium. On the other hand after osmotic shock the uptake of dopamine into the particles of this fraction was greatly enhanced by addition of ATP and magnesium. The uptake of dopamine into the particles of both intact and osmotically shocked 80000 g fractions was likewise enhanced by ATP and magnesium. The uptake in all fractions was not influenced by ouabain. The influx of dopamine into the particles of the intact 80000 g fraction was competitively inhibited by reserpine (Ki0.96 x 10-8M) and prenylamine (Ki1.74 x 10-8M). It is concluded that the intact 20000 g fraction contains intact synaptosomes; the uptake of dopamine is independent of the presence of ATP and magnesium. The shocked 20000 g fraction and the 80000 g fractions contain synaptic vesicles; the uptake of dopamine into these vesicles is enhanced by ATP and magnesium.

Adenosine Triphosphate↗
PubMedDate not supplied

Anticancer activity of rViscumin (recombinant mistletoe lectin) in tumor colonization models with immunocompetent mice.

The antitumoral and immunostimulating properties of rViscumin (recombinant mistletoe lectin) were investigated in two mouse tumor models. After intravenous inoculation with RAW-117-P or L-1 sarcoma cells in Balb/c mice, rViscumin was given s.c. at non-toxic doses ranging from 0.3 to 150 ng rViscumin/kg. One set of experiments was performed to investigate the survival of rViscumin-treated animals. Another set was carried out to analyze the effect of rViscumin treatment on the number of tumor colonies in infiltrated lungs (RAW-117P) or liver (L-1) and the activation of immune cell subsets, respectively. An overall prolonged survival time after treatment with rViscumin and a reduction in the number of tumor colonies after administration of certain rViscumin doses was observed. Immunophenotyping of the peripheral leukocytes of treated mice revealed increased numbers of T-lymphocytes, pan-NK cells and activated monocytes. The results indicate that rViscumin has antineoplastic properties and might therefore be a promising candidate in cancer therapy.

Adjuvants, Immunologic↗
PubMedDate not supplied

A natural immunity-activating plant lectin, Viscum album agglutinin-I, induces apoptosis in human lymphocytes, monocytes, monocytic THP-1 cells and murine thymocytes.

A galactoside-specific plant lectin, Viscum album agglutinin-I (VAA-I) with protein synthesis-inhibiting properties, has been shown to be cytotoxic in various eukaryotic cells, in vitro above a 10 ng/ml concentration. Noncytotoxic concentrations of VAA-I induced mRNA expression and enhanced secretion of proinflammatory cytokines in cultures of human peripheral blood mononuclear cells. In an animal model VAA-I has been shown to stimulate natural killer cells and granulocytes. In this study, human peripheral blood lymphocytes (PBL), human peripheral blood monocytes (PBM), murine thymocytes and human monocytic THP-1 cells were incubated for 24 h in the presence of various concentrations of VAA-I. The apoptotic effect of VAA-I was analyzed by flow cytometry following staining of the apoptotic nuclei in the cells with PI in hypotonic buffer and quantitative detection of DNA breaks were analyzed by the terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end-labeling (TUNEL) assay. In cultures of all types of investigated cells, a dose-dependent VAA-I concentrations above 10 ng/ml in PBL and at 1 ng/ml VAA-I concentration in PBM, thymocytes and THP-1 cells, a lectin-induced increase of the apoptotic nuclei was observed. In 24-hour cultures of PBL and thymocytes, the ratios between apoptotic and nonapoptotic cells were enhanced 10 times and 8 times, respectively, by 100 ng/ml VAA-I compared to the negative control. The concentration of 100 micrograms/ml VAA-I only caused necrosis. The isolated A chain of the VAA-I induced apoptosis in PBL and thymocytes. In the culture of PBL the isolated B chain of the VAA-I was not effective indicating that cytokine induction by VAA-I is probably not involved in its apoptotic effect. On CD4+8+ thymocytes, VAA-I resulted in a reduced expression of CD8+ molecules that could be related to a loss of volume and increase of density, both characteristic features of apoptosis.

Animals↗