Axenic cultivation of Entamoeba histolytica: progress and problems.

Eighteen years of technological progress in the field of axenic cultivation of Entamoeba histolytica is reviewed. During this period cumbersome diphasic media gave way to easily prepared clear liquid media. Yields of amebae were increased a thousand fold, and doubling time reduced from 24 to less than 8 hours.

[3-(1,4-Cyclohexadienyl)-L-alanine,8-lysine]vasopressin: synthesis and some pharmacological properties.

[3-(1,4-Cyclohexadienyl)-L-alanine,8-lysine]vasopressin, otherwise known as [3-(2,5-dihydrophenylalanine),8-lysine]vasopressin or [DiHPhe3]lysine-vasopressin, has been synthesized in an attempt to utilize 2,5-dihydrophenylalanine (DiHPhe) to evaluate the contribution of aromaticity in position 3 to biological activity. The analogue has the same primary structure as lysine-vasopressin, except that two additional hydrogen atoms are present on the ring moiety of the phenylalanine residue in position 3. The key intermediate was the protected nonapeptide N-carbobenzoxy-S-benzyl-L-cysteinyl-L-tyrosyldihydrophenyl-L-alanyl-L-glutaminyl-L-asparaginyl-S-benzyl-L-cysteinyl-L-prolyl-N epsilon-tosyl-L-lysylglycinamide that was synthesized stepwise by the solid-phase technique.

Ornithine decarboxylase activity and DNA synthesis after treatment of cells in culture with 12-O-tetradecanoylphorbol-13-acetate.

The ability of the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) to induce the enzyme ornithine decarboxylase (ODC) and to stimulate DNA synthesis was studied in four different cell types in vitro. The effects of this agent on each cell type were different: (a) in hamster embryo cells, TPA induced ODC but had no effect on DNA synthesis; (b) TPA induced ODC and stimulated DNA synthesis in BALB/c 3T3 mouse cells; (c) it did not induce ODC in human fibroblasts but did stimulate DNA synthesis; and (d) it induced neither ODC nor DNA synthesis in rat embryo fibroblasts. In contrast to the effects of TPA, ODC was induced and DNA synthesis was stimulated in all cell types by fresh serum-containing medium.

Immune suppression of erythropoiesis in transient erythroblastopenia of childhood.

Serum and IgG from four children with transient erythroblastopenia of childhood (TEC) was tested to see what effect it would have on development of erythroid colonies from bone marrow mononuclear cells. Serum and IgG specimens obtained at the time of diagnosis uniformly suppressed erythroid colony development from CFU-E. Washed bone marrow mononuclear cells from a child with TEC failed to grow in the presence of his own serum, but grew normally in the presence of isologous serum.

Cell surface markers on lymphoid cells from Warthin's tumors.

T- and B-cell markers were studied on suspensions of lymphoid cells obtained from two Warthin's tumors. Each tumor was composed predominantly of T- lymphocytes and a smaller percentage of B-lymphocytes with a polyclonal distribution of their surface immunoglobulin. These results do not differ from those obtained in normal or reactive lymph nodes.

Experimental amebiasis. IV. Amebal viruses and the virulence of Entamoeba histolytica.

We have attempted to determine whether amebal viruses are capable of viral conversion of the virulence of Entamoeba histolytical. Amebae of little or no virulence for the newborn hamster liver were infected with viruses obtained from four amebal strains of different virulence. Cultures of surviving amebae were increased in virulence by viruses from amebae of high, moderate, or low virulence, but decreased in virulence by the virus of the second most pathogenic amebal strain.

Induction of differentiation in human promyelocytic leukemia cells by tumor promoters.

Phorbol diester tumor promoters and the promoter mezerein convert human promyelocytic leukemia cells in culture into adherent, nonproliferating cells with many of the characteristics of macrophages. Other types of promoters such as anthralin, phenobarbital, and saccharin do not have this effect. Various compounds that can inhibit some of the biological and biochemical effects of tumor promoters do not interfere with the induction of cell adherence and differentiation by the effective promoters.

Mechanism of L-serine oxidation in Entamoeba histolytica.

1. The enzymatic mechanism of oxygen uptake elicited by L-serine in axenically cultivated trophozoites of Entamoeba histolytica was investigated. 2.

The effects of exogenous norepinephrine on ventilatory mechanics in the rat.

The effects of intravenous administration of norepinephrine on ventilatory mechanics were assessed in the anesthetized, spontaneously breathing rat. Pulmonary resistance, dynamic compliance and functional residual capacity remained unchanged during a 10-min infusion period. After paralysis, repetition of the norepinephrine infusion caused an increase in static deflation recoil pressure at lung volumes above the tidal range but maximum expiratory flow rates at corresponding lung volumes were not increased indicating an elevation in the resistance of upstream airways.

Clonal growth of Entamoeba histolytica and other species of Entamoeba in agar.

This is the first description of a method for growing axenized Entamoeba histolytica as colonies from single cells in agar suspension. Factors affecting the efficiency of colony formation included unknown characteristics of the amebal strain, age of cells used, and the type and concentration of agar employed. Colony formation was dependent upon filling deep vessels (culture tubes or tissue culture flasks) with agar, probably to maintain reduced oxygen tension, and upon solidifying the agar rapidly at 0 C.

Active bronchial anaphylaxis in the rat: inhibition by tiaramide.

Intravenous administration of the benzothiazoline derivative tiaramide hydrochloride, to rats actively sensitized to ovalbumin, inhibited immunologic lung reactions in a dose-related manner. Methysergide also inhibited anaphylactic lung reactions. Serotonin, but not other chemical mediators, produced changes in pulmonary mechanics qualitatively similar to those produced by the sensitizing antigen.

Formation of glucuronic acid conjugates of 7,12-dimethylbenz(a)anthracene phenols in 7,12-dimethylbenz(a)anthracene-treated hamster embryo cell cultures.

Secondary cultures of hamster embryo cells exposed to 0.5 nmol [G-3H]7,12-dimethylbenz(a)anthracene (DMBA) per ml medium metabolized more than 90% of the DMBA within 48 hr. Samples of medium were extracted with chloroform, methanol, and water.

Metabolism of tritium-labeled 12-O-tetradecanoylphorbol-13-acetate by cells in culture.

The metabolism of [20-3H]-12-O-tetradecanoylphorbol-13-acetate ([3H]TPA) was studied in human and hamster cell cultures. Within 2 to 3 days after its addition to growing or confluent cultures of hamster embryo fibroblasts, no unchanged [3H]TPA remained in the medium as determined by thin-layer chromatography of the chloroform phase obtained by extraction of the medium with chloroform:methanol:H2O. In contrast, little or no metabolism of [3H]TPA occurred under identical conditions in cultures of human fibroblasts.

Long-term oral bronchodilator therapy of asthma with pirbuterol.

We studied the effects of an oral beta2 selective bronchodilator, pirbuterol, in 12 male asthmatic patients over periods ranging from 6 to 23 months (mean, 13.8). Each patient was evaluated initially by physical examination, urinalysis, blood analysis, and pulmonary function tests.