Free and polymerized tubulin in cultured bone cells and Chinese hamster ovary cells: the influence of cold and hormones

A low pH method of liposome-membrane fusion (Schneider et al., 1980, Proc. Natl. Acad. Sci. U. S. A. 77:442) was used to enrich the mitochondrial inner membrane lipid bilayer 30-700% with exogenous phospholipid and cholesterol. By varying the phospholipid-to- cholesterol ratio of the liposomes it was possible to incorporate specific amounts of cholesterol (up to 44 mol %) into the inner membrane bilayer in a controlled fashion. The membrane surface area increased proportionally to the increase in total membrane bilayer lipid. Inner membrane enriched with phospholipid only, or with phospholipid plus cholesterol up to 20 mol %, showed randomly distributed intramembrane particles (integral proteins) in the membrane plane, and the average distance between intramembrane particles increased proportionally to the amount of newly incorporated lipid. Membranes containing between 20 and 27 mol % cholesterol exhibited small clusters of intramembrane particles while cholesterol contents above 27 mol % resulted in larger aggregations of intramembrane particles. In phospholipid-enriched membranes with randomly dispersed intramembrane particles, electron transfer activities from NADH- and succinate-dehydrogenase to cytochrome c decreased proportionally to the increase in distance between the particles. In contrast, these electron- transfer activities increased with decreasing distances between intramembrane particles brought about by cholesterol incorporation. These results indicate that (a) catalytically interacting redox components in the mitochondrial inner membrane such as the dehydrogenase complexes, ubiquinone, and heme proteins are independent, laterally diffusible components; (b) the average distance between these redox components is effected by the available surface area of the membrane lipid bilayer; and (c) the distance over which redox components diffuse before collision and electron transfer mediates the rate of such transfer.     

Radioimmunoassay of low molecular weight human kininogen

A radioimmunoassay for low molecular weight (LMW) human Kininogen has been carried out. The first step was to prepare LMW Kininogen from human plasma. The proposed method allowed to get chemically pure and biologically active LMW Kininogen. This preparation was used to induce antibody. Optimal conditions for labelling and incubation were determined. This method may be applied to the assay of Kininogen in human plasma.     

Prekallikrein and kininogens in blister fluids in burn patients

Blister fluids removed from benign cutaneous burns contain the components of the prekallikrein-kininogens system in a non activated state. Their occurrence in the fluids is explained by a diffusion from the blood plasma.     

Movements and associations of ribosomal subunits in a secretory cell during growth inhibition by starvation

In Chironomus tentans salivary gland cells, the cytoplasm can be dissected into concentric zones situated at increasing distances from the nuclear envelope. After RNA labeling, the newly made ribosomal subunits are found in the cytoplasm mainly in the neighborhood of the nucleus with a gradient of increasing abundance towards the periphery of the cell. The gradient for the small subunit lasts for a few hours and disappears entirely after treatment with puromycin. The large subunit also forms a gradient but one which is only partially abolished by puromycin. The residual gradient which which is resistant to the addition of the drug is probably due to the binding of some large ribosomal units to the membranes of the endoplasmic reticulum (J.-E. Edstrom and u. Lonn. 1976. J. Cell Biol. 70:562-572, and U. Lonn and J.-E. Edstrom. 1976. J. Cell. Biol. 70:573-580). If growth is inhibited by starvation, only the puromycin-sensitive type gradient is observed for the large subunit, suggesting that the attachment of these newly made subunits to the endoplasmic reticulum membranes will not occur. If, on the other hand, the drug-resistant gradient is allowed to form in feeding animals, it is conserved during a subsequent starvation for longer periods than in control feeding animals. This observation provides a further support for an effect of starvation on the normal turnover of the large subunits associated with the endoplasmic reticulum. These results also indicate a considerable structural stability in the cytoplasm of these cells worth little or no gross redistribution of cytoplasmic structures over a period of at least 6 days.     

Inhibition of the prostaglandin-liberating activity of bradykinin in the rat]

In the rat, hydrocortisone, dexamethasone and chloroquine do not inhibit the hypotensive activity of arachidonic acid, which is due to endogenous prostaglandin synthesis. They reduce or suppress the secondary hypotensive phase induced by bradykinin. These substances inhibit the prostaglandin releasing activity of bradykinin but do not interfere with prostaglandin synthesis.     

Inhibition of lysosomal enzyme liberation by indomethacin in vivo

The volume of the peritoneal exudate induced in the rat by iota carrageenan is reduced by subcutaneous administration of indomethacin while the concentrations of three lysosomial enzymes in the exudate are slightly increased or not modified. Thus, the total enzymatic activities of the exudate are reduced by indomethacin. The leucocyte accumulation remains unchanged in the indomethacin treated rats. During the development of the peritoneal exudate, the circulating plasma displays a high degree of lysosomial enzymes activity which is suppressed by indomethacin at the dose of 4 mg/kg.     

Formation of human immunoreactive LMW and HMW-kininogens during coagulation. Comparison with bradykinin activity

Variations of the levels of human HMW and LMW kininogens have been studied in serum and in plasma incubated in vitro during 30 hours, at three different temperatures: 4 degrees, 22 degrees and 37 degrees C. There is a small difference between the level of LMW kininogen in plasma and in serum, but the serum and plasma level of LMW kininogen are almost stable during the time of incubation at the three temperatures. However, HMW kininogen is reduced in serum to about fifty percent of its plasma level. It decreases in plasma and in serum during incubation, overall at 4 degrees C. A strict parallelism stays between the radioimmunoassay and the bioassay.     

Cytochrome c4 from Pseudomonas aeruginosa

The dihaem cytochrome c₄ from Pseudomonas aeruginosa has been crystallized in space group P6₅22 with cell dimensions $\text{a = b = 62.4}\text{A}\text{?}\text{, c = 174.2}\text{A}\text{?}$, and one molecule per asymmetric unit. Two heavy-atom derivatives, UO₂(NO₃)₂ and K₂Pt(NO₂)₄, which substitute at one and three sites, respectively, have allowed a low-resolution electron density map to be obtained. This shows clearly the two domains of the molecule.     

Interaction of polymorphonuclear leukocytes, bradykinin and carragenin. Transference reaction in the rat

1. Injected in the paw of the rat, polymorphonuclear leucocytes do not increase the oedematogen action of bradykinin, but increase the action of lambda carrageenan. 2. This potentiation of carrageenan action is not modified when PG biosynthesis in leucocytes is inhibited by indomethacin or aspirin. It does not appear in rats previously treated by indomethacin or aspirin. 3. Our results suggest that rat polymorphonuclear leucocytes increase the inflammatory reaction, when they are stimulated by carrageenan, by the release of a phospholipase A2 activity which induces PG biosynthesis in rat paw tissues.