Parameters affecting the in vitro maturation of human monocytes to macrophages

In vitro maturation of human monocytes to macrophages was characterized by morphological criteria, cell size and lysosomal enzymes activity. Purified populations of monocytes were maintained in culture at either adherent or nonadherent conditions and their maturation to macrophages was observed in both cases. The addition of external factors such as hydrocortisone and vitamin D3 inhibited monocyte maturation. In the absence of external factors, nonadherent monocytes were inhibited in their maturation for up to 10 days when plated at crowded cell concentrations. In addition, the presence of human serum in the culture media had a higher inhibitory activity than similar concentrations of fetal calf serum. Supernates from crowded macrophages were also inhibitory for monocyte maturation. We suggest the possibility that cell crowding, as well as soluble factors found in the serum and probably secreted by macrophages, participate in the regulation of monocyte development by inhibiting their maturation. Once released from this inhibitory signal or environment, the monocytes mature to macrophages.     

The 131I Ortho-iodohippurate Photoscan in Human Renal Allografts

Nine examples, in seven patients, from a large cadaver renal allograft program, illustrate the value of radio-hippuran photoscans in differentiating causes of post-implant oliguria. Hippuran scans are shown to be more valuable than chlormerodrin scans when renal function is acutely depressed. Hippuran scans aided in the decision to remove kidneys in four cases of severe oliguria and to retain kidneys in two others. In two further examples, extravasation of urine was detected by scanning after radio-hippuran injection when other tests had failed to do so.The technique of radio-hippuran scanning has a place in the differentiation of acute and subacute renal dysfunction and has proved particularly valuable in the early oliguric complications of a cadaver renal transplant program.     

Decreased levels of serum platelet-activating factor acetylhydrolase in patients with rheumatic diseases

PAF is a potent inflammatory compound known to stimulate the release of various cytokines involved in rheumatic diseases. Elevated blood PAF levels are reported in these patients. We report that serum PAF acetylhydrolase activity (AHA) levels are decreased in patients with rheumatoid arthritis or osteoarthritis as compared to healthy controls. Serum and synovial fluid AHA levels were correlated in these patients. The present study suggests the potential role of AHA in controling systemic and/or local PAF levels in patients with rheumatic diseases.     

Gonadotropin response to slow infusion of GN-RH in idiopathic ologospermia. Preliminary findings

Gn-RH was administered i.v. to infertile patients presenting with idiopathic oligospermia at a constant rate (0,4 microgram) for 4 h. All the patients showed an increased FSH response, and LH levels higher than normal in both the first and the second peak of response. Our data indicate that an increased pituitary sensitivity and reserve of FSH and LH are present in idiopathic oligospermia, suggesting an involvement of both Leydig cells and seminiferous epithelium in this condition.     

The generation of the proton electrochemical potential and its role in energy transduction

Summary The evidence that all energy transducing membranes can generate a proton electrochemical potential difference, _H, across the membrane and that this potential can be used to transfer energy among energy transducing units and to generate ATP, has increased the interest for the view that _H plays an obligatory role in energy transduction and ATP synthesis. In the present article we shall concentrate on two experimental questions related with the generation and role of _H: (a) the charge/site ratio; (b) the relation between the proton electrochemical potential on one side and the cation electrochemical potential, the phosphate potential and the redox potential on the other. We shall then discuss the view that energy transduction corresponds to a molecular energy machine rather than to a fuel cell.     

Characterization of calcium-triggered secretion in permeabilized rat basophilic leukemia cells. Possible role of vectorially acting G proteins.

Strong, albeit indirect, evidence suggests that a GTP-binding (G) protein(s) can act directly on the secretory machinery by a post-second messenger mechanism. The type and function of this putative Ge (exocytosis) protein were investigated in streptolysin-O-permeabilized rat basophilic leukemia (RBL) cells. The exocytotic response to calcium was first characterized both morphologically and biochemically using the release of preloaded [3H]serotonin as an index of exocytosis. Calcium-induced secretion (EC50 about 3 microM) in RBL cells requires ATP (EC50 about 2.5 mM) and is modulated by pH, the optimal value being 7.2. Another requirement for calcium-induced secretion is an activated G protein, since inactivators of G proteins such as GDP beta S (EC50 about 800 microM) inhibit the secretagogue effect of 10 microM free calcium. Conversely, GTP gamma S (EC50 about 1 microM) and other nonhydrolyzable analogs of GTP, which keep G proteins in a permanently active conformation, potentiate the effect of calcium. GTP gamma S alone is without effect. The effect of GTP gamma S on exocytosis is apparently not mediated by known second messengers, suggesting that a Ge protein is involved. Electron microscopic images show that in resting cells, secretory granules are clustered in the perinuclear area, whereas they become scattered upon calcium stimulation. A paradoxical effect of GTP gamma S is observed when applied during permeabilization; under these conditions, in fact, the nucleotide inhibits the subsequent secretory response to calcium. The scattering of granules is also inhibited. This effect of GTP gamma S is counteracted by coadministration of GTP. These responses to guanine nucleotides are typical of vectorially acting G proteins involved in protein synthesis and in intracellular vesicle transport. Taken together, the data presented suggest that calcium-dependent release requires a vectorially acting G protein controlling the movement of secretory granules. This and alternative models are discussed.     

Ascorbate peroxidase activity in resistant and susceptible plants of Lycopersicon esculentum.

Activity of redox-enzymes of AA system and of catalase was measured in two near-isogenic tomato lines, respectively resistant and susceptible to Tobacco Mosaic Virus infection. AFR reductase, DHA reductase and catalase showed quite similar activities in both lines, whereas AA peroxidase activity in resistant plants was 75% higher than in susceptible ones, with Km values about 4-fold lower. These data suggest that hydrogen peroxide scavenging operated by AA peroxidase could play an important role in the development of biological defence mechanisms against pathogens.     

Cytotoxic T-lymphocyte and spontaneous killer cell activity against human T- and B-lymphoid cell lines.

We have investigated cell-mediated immune responses to cultured human T- and B-cell lines. Two effector mechanisms were explored and found to have different capabilities for mediating cytotoxic reactions. Cytotoxic T lymphocytes were generated by stimulation with irradiated B-cell lines and demonstrated cross-reactive cytotoxicity against these lines but not against T-cell lines. Unseparated mononuclear cells showed spontaneous cytotoxicity for both T- and B-cell lines; however, T-cell lines appeared more susceptible. Cell separation procedures were employed to determine functional differences in effector cells. In contrast to cytotoxic T lymphocytes induced in vitro, spontaneous killer cells (SKC) were shown to be nylon wool adherent, non-T lymphocytes with receptors for IgG-coated sheep erythrocytes.