Search results for "tritium"

Hydrogeological Behaviour and Geochemical Features of Waters in Evaporite-Bearing Low-Permeability Successions: A Case Study in Southern Sicily, Italy

2020

Knowledge about the hydrogeological behaviour of heterogeneous low-permeability media is an important tool when designing anthropogenic works (e.g., landfills) that could potentially have negative impacts on the environment and on people&rsquo

Regulatory factor for the transcription of the ribosomal genes in amphibian oocytes.

1970

AMPHIBIAN oocytes provide very convenient material for the study of the mechanisms that control ribosomal RNA synthesis because their pattern of ribosomal RNA synthesis does not change greatly during oogenesis. During the lampbrush stage of oogenesis (stage 4) more than 97 per cent of the RNA synthesized per unit time in the oocytes is ribosomal. This happens because the genes for ribosomal RNA are specifically amplified3–5 to such an extent that the oocyte nucleus (germinal vesicle) has an rDNA content approximately 1,500 times more than the haploid amount4. On the other hand, in mature oocytes (stage 6) no ribosomal RNA is synthesized1,2, although the extra copies of the ribosomal cistron…

Implication of three isoforms of PLA2in human T-cell proliferation

2002

We observed that human (Jurkat) T-cells constitutively expressed the mRNA, encoding for the four isoforms of phospholipase A(2) (PLA(2)), i.e. two secretory (type IB and type V), and two cytosolic (type IV, Ca(2+)-dependent and type VI, Ca(2+)-independent). In order to assess whether these PLA(2) isoforms are active, we labeled Jurkat T-cells with [(3)H]arachidonic acid ([(3)H]AA) and determined its release into the extracellular medium in the presence of phorbol 12-myristate 13-acetate (PMA) and ionomycin. The three PLA(2) isoforms seem functional as aristolochic acid and bromoenol lactone (BEL), the respective inhibitors of type IB/type V and type VI PLA(2)s, significantly inhibited the r…

Small unilamellar liposomes from mixed natural and polymeric phospholipids: stability and susceptibility to phospholipase A2.

1991

The concept of the uncorkable liposome composed of phase-separated mixtures of a polymerized phospholipid and an enzymically digestible phospholipid has been investigated, using small unilamellar vesicles composed of mixtures of (polymerized) dienoylphosphatidylcholine (DENPC) and dimyristoylphosphatidylcholine (DMPC). Mixed liposomes, even those containing only 10% DENPC, were much more stable than DMPC liposomes, as indicated by the release of entrapped [3H]inulin or [14C]glucose. DMPC liposomes released entrapped solute on exposure to phospholipase A2, whereas mixed vesicles were resistant. The results are compared with those of an earlier study on monolayers of similar compositions. It …

Platelet Activation: a New Biological Activity of Guinea-pig C3a Anaphylatoxin

1978

3H-serotonin-release from labelled gp-platelets is established as a sensitive method for testing a new biological activity of gp-C3a anaphylatoxin in an autologous situation. Time-, dose- and temperature-dependent release reactions as well as specific inhibition by carboxypeptidase B and anti-C3a antibodies show that C3a is a potent and specific inducer of platelet activation. Inactive C3a does not induce 3H-serotonin-release but specifically inhibits the action of C3a on platelets.

Calibration of misonidazole labeling by simultaneous measurement of oxygen tension and labeling density in multicellular spheroids

1995

To correlate misonidazole concentrations and oxygen pressures (Po2) at identical locations within EMT6/Ro multi-cell spheroids (mean diameters +/- SD: 867 +/- 20 microns), Po2 measurements were performed with oxygen-sensitive microelectrodes during incubation of these spheroids with tritiated misonidazole (10 mg/I; 445 microCi/mg). In each individual spheroid, Po2 profiles were correlated with the corresponding spatial distribution of misonidazole as quantified by conventional autoradiography and grain counting. To compare the oxygenation status of spheroids in the measuring chamber with that of spheroids in spinner culture, misonidazole labeling was performed in both environments following…

3H-estradiol and3H-R5020 binding in cytosols of normal and neoplastic human ovarian tissue

1983

High-affinity cytoplasmic estrogen and progesterone receptors in normal and abnormal ovarian tissues were studied. Estradiol receptor was detectable in 65% and progesterone receptor in 36% of the malignant tumors; 39% of all malignant ovarian tissues were estradiol- as well as progesterone-receptor-positive. Tumors were said to be receptor-positive when the receptors bound greater than 5 fM steroid/mg cytosol protein. No correlations were found between receptor status and histopathological diagnosis. In normal ovarian tissues collected at various phases of the menstrual cycle no changes in [3H]-estradiol and [3H]-R5020 binding could be detected. Analysis of the receptor concentration for bo…

RIBOSOMAL SUBUNIT EXCHANGE IN DICTYOSTELIUM PURPUREUM

1970

Binucleate cells in the Ehrlich ascites tumor. Autoradiographic labeling

1989

Abstract An autoradiographic study was performed on binucleate and mitotic cells in the Ehrlich ascites tumor (EAT) untreated and after treatment with 5-fluorouracil (FU). The number of binucleate cells was greater in the treated tumor than in the controls. It was also observed that the number of labeled mitoses was greater in the Fu-treated tumor. Autoradiographic labeling showed that the cells that proved to be binucleate had previously passed through S-phase; thus, these cells belonged to the proliferative compartment.

Primary Neural Precursors and Intermitotic Nuclear Migration in the Ventricular Zone of Adult Canaries

1998

New neurons continue to be born in the ventricular zone (VZ) of the lateral ventricles in the brain of adult birds. On the basis of serial section reconstruction and electron microscopy, we determined that the VZ of the adult canary brain is composed of three main cell types (A, B, and E). Type A cells were never found in contact with the ventricle and had microtubule-rich processes typical of young migrating neurons. Type B cells were organized as a pseudostratified epithelium, all contacted the ventricle, and most had a characteristic single cilium. Type E cells, also in contact with ventricle, were ultrastructurally similar to the mammalian multiciliated ependymal cells. After six inject…