Microsomal and cytosolic epoxide hydrolases, the peroxisomal fatty acid beta-oxidation system and catalase. Activities, distribution and induction in rat liver parenchymal and non-parenchymal cells

A number of structurally unrelated hypolipidaemic agents and certain phthalate-ester plasticizers induce hepatomegaly and proliferation of peroxisomes in rodent liver, but there is relatively limited data regarding the specific effects of these drugs on liver non-parenchymal cells. In the present study, liver parenchymal, Kupffer and endothelial cells from untreated and fenofibrate-fed rats were isolated and the activities of two enzymes associated with peroxisomes (catalase and the peroxisomal fatty acid beta-oxidation system) as well as cytosolic and microsomal epoxide hydrolase were measured. Microsomal epoxide hydrolase, cytosolic epoxide hydrolase and catalase activities were 7-12-fold higher in parenchymal cells than in Kupffer or endothelial cells from untreated rats; the peroxisomal fatty acid beta-oxidation activity was only detected in parenchymal cells. Fenofibrate increased catalase, cytosolic epoxide hydrolase and peroxisomal fatty acid beta-oxidation activities in parenchymal cells by about 1.5-, 3.5- and 20-fold, respectively. The induction of catalase (2-3-fold) and cytosolic epoxide hydrolase (3-5-fold) was also observed in Kupffer and endothelial cells; furthermore, a low peroxisomal fatty acid beta-oxidation activity was detected in endothelial cells. Morphological examination by electron microscopy showed that peroxisomes were confined to liver parenchymal cells in untreated animals, but could also be observed in endothelial cells after administration of fenofibrate.     

The Stochastic Theory of Cell Proliferation

A stochastic theory of cell kinetics has been developed based on a realistic model of cell proliferation. A characteristic transit time, _i, has been assigned to each of the four states (G₁, S, G₂, M) of the cell cycle. The actual transit time, t_i, for any cell is represented by a distribution around _i with a variance σ_i². Analytic and computer formulations have been used to describe the time development of such characteristics as age distribution, labeling experiments, and response to perturbations of the system by, for example, irradiation and temperature. The decay of synchrony is analyzed in detail and is shown to proceed as a damped wave. From the first few peaks of the synchrony decay one can obtain the distribution function for the cell cycle time. The later peaks decay exponentially with a characteristic decay constant, λ, which depends only on the average cell-cycle time, , and the associated variance. It is shown that the system, upon any sudden disturbance, approaches new “equilibrium” proliferation characteristics via damped periodic transients, the damping being characterized by λ. Thus, the response time of the system, /λ, is as basic a parameter of the system as the cell-cycle time.     

Morphology and Reproductive Processes of the L Forms of Bacteria II. Comparative Study of L Forms and Mycoplasma with the Electron Microscope

Representative electron micrographs, from the study of eight strains of L forms and one strain of Mycoplasma, are presented. A- and B-type L forms were derived from two strains of Proteus, two other L forms were derived from a diphtheroid and from a staphylococcus strain, and two strains (designated as LX) were isolated from L forms derived from a group A beta-hemolytic streptococcus and from a staphylococcus. The Mycoplasma strain was isolated from goats. Sections were made of young colonies grown within agar and from parts of surface colonies embedded in the agar. B-type L colonies of Proteus were produced by inoculation of bacteria into media containing penicillin. The large bodies developing from the bacteria and the organisms in B-type L colonies of Proteus, like the parent bacteria, had a cell wall consisting of a plasma membrane and an outer cell wall. The loss of rigidity in the cell wall indicated an alteration in its structure. The A-type L cultures of Proteus consisted of irregular branching masses extending in several directions, of small dense organisms corresponding to the elementary corpuscles present in cultures of Mycoplasma, and of intermediary forms. In contrast to the B-type, all organisms in the A-type colonies were surrounded by a single unit membrane corresponding to the plasma membrane of bacteria. The structures inside the cell membrane, both in the A- and B-type, seemed to correspond to the structure of the parent bacteria, which contained ribosomes and threads of DNA. The elementary corpuscles formed chains and filaments, and, apparently, these corpuscles took part in the multiplication by gradual enlargement. The organisms seen in the cultures of all L forms and Mycoplasma studied, except in the B-type L forms of Proteus, corresponded in size, shape, and structure, as well as in the development of elementary corpuscles, to the organisms in the A-type L form of Proteus. In contrast to the spherical organisms usually seen in broth cultures, the organisms in young cultures of Mycoplasma, which were grown within the agar, were similar in morphology, as well as in the discernible structure of the organisms, to L forms. Significant morphological and structural differences were not apparent between the L forms and Mycoplasma (in cultures grown within agar media) under the conditions of this investigation.     

Production of an insulin-like growth factor by osteosarcoma

To test the possibility that osteosarcoma cells produce their own growth factors, we measured levels of insulin and somatomedin C (SMC), an insulin-like growth factor, in culture media of two cell lines derived from patients with that disease. SMC but not insulin levels increased three- to ten-fold over a period of 7 days paralleling the increases in cell number. Production of SMC was inhibited by cycloheximide.     

Bidirectional Transfer between Metaphorical Related Domains in Implicit Learning of Form-Meaning Connections

People can implicitly learn a connection between linguistic forms and meanings, for example between specific determiners (e.g. this, that…) and the type of nouns to which they apply. Li et al (2013) recently found that transfer of form-meaning connections from a concrete domain (height) to an abstract domain (power) was achieved in a metaphor-consistent way without awareness, showing that unconscious knowledge can be abstract and flexibly deployed. The current study aims to determine whether people transfer knowledge of form-meaning connections not only from a concrete domain to an abstract one, but also vice versa, consistent with metaphor representation being bi-directional. With a similar paradigm as used by Li et al, participants learnt form- meaning connections of different domains (concrete vs. abstract) and then were tested on two kinds of generalizations (same and different domain generalization). As predicted, transfer of form-meaning connections occurred bidirectionally when structural knowledge was unconscious. Moreover, the present study also revealed that more transfer occurred between metaphorically related domains when judgment knowledge was conscious (intuition) rather than unconscious (guess). Conscious and unconscious judgment knowledge may have different functional properties.     

Modulation of MUC1 and blood group antigen expression in gastric adenocarcinoma cells by cytokines

Immunohistological studies demonstrated that MUC1 expression in gastric cancer is associated with a poor prognosis. As a mediator of cell-cell interactions, MUC1 may also be involved in metastasis. However, these aspects are of relevance since cytokine levels are locally increased as a consequence of peritumorous inflammatory response and coexisting chronic gastritis. Therefore we analyzed the potential influence of several cytokines on the expression of tumor-associated MUC1 and Lewis blood group antigens in gastric carcinoma cells. Gastric cancer cell lines AGS and KATOIII were incubated with the cytokines interleukin-1beta, interferon-gamma, tumor necrosis factor-alpha (TNF-alpha), and hepatocyte growth factor over a period of 72 h. Expressions of mucin antigens and cytokine secretion were measured by immunocytochemistry and/or enzyme-linked immunosorbent assay (ELISA). Analysis by fluorescence-activated cell sorter (FACS) demonstrated that MUC1 and sialyl Lewis A reactivities of AGS cells were increased significantly following TNF-alpha stimulation but not by other cytokines. Expression of mucin-associated antigens by cell line KATOIII was not affected by any of the employed cytokines. These data provide evidence that TNF-alpha can raise the expression of important mucin peptide as well as mucin-associated carbohydrate antigens and thereby potentially influence the progression of gastric carcinomas.     

Mitochondrial localization and temporal expression of the Drosophila melanogaster DnaJ homologous tumor suppressor Tid50

The Drosophila melanogaster tumor suppressor gene lethal(2)tumorous imaginal discs (tid) was identified as a homolog of all dnaJ-like genes known to date which have been well preserved in evolution. Homozygous D. melanogaster l(2)tid mutants l(2)tid¹, l(2)tid² and l(2)tid³ are characterized by neoplastic transformation of the adult integumental primordia, the imaginal discs, and the death at the time of puparium formation. The first part of this study is concerned with the identification and subcellular localization of the l(2)tid-encoded protein, Tid50. The second part examines its tissue specific expression during wild-type development and in tumorous imaginal discs. To specify the function(s) of the Tid50 protein polyclonal rabbit antibodies directed against various domains of it were generated and used for staining of Western blots and whole-mounts and paraffin sections of various tissues isolated from wild-type and mutant tumor-developing animals. To identify the mutational events leading in homozygous l(2)tid mutants to abnormal expression level of l(2)tid-encoded RNA and protein, the mutant gene was isolated from homozygous l(2)tid¹ and l(2)tid² animals and sequenced.