A macrophage derived blastogenic factor -MBF- induces cytokines and cytotoxic effectors in human peripheral blood mononuclear cells.

A soluble macrophage-derived blastogenic factor, previously reported as MBF, is secreted from macrophages activated with galactose oxidase. It was previously shown that MBF is able to induce IFN-gamma production and proliferation of T lymphocytes. In this study we found that MBF is able to induce in human peripheral blood mononuclear cells (PBMC) production of interleukin 1 (IL-1) beta, interleukin 2 (IL-2) and tumor necrosis factor (TNF) alpha and generation of MHC-unrestricted cytotoxic activity. The induction of killer cells is likely to rely on IFN-gamma production in that in PBMC treated with a monoclonal antibody (Mab) against IFN-gamma, the MBF induced cytotoxic activity was drastically reduced. A comparison of MBF induced cytotoxic effectors with those induced by IL-2 showed that both cytotoxic effectors pertain to NK lineage, in that they were CD3- and CD16+. On the contrary, the precursors of MBF and IL-2 induced killer cells were different; MBF cytotoxic precursor cells were highly sensitive to L-Leucine methyl ester (Leu-OME), a drug able to eliminate monocytes and NK cells, whereas IL-2 cytotoxic precursors were unaffected by this drug.     

Expression of the autosomal folate-sensitive fragile sites in ten kindreds with Martin-Bell syndrome

The authors analyse the expression of all the folate-sensitive fra sites in a sample of 24 male patients with Martin-Bell syndrome (MBS) and their 12 mothers distributed in 10 kindreds. The cytogenetic results are compared with that of a control group, constituted by 8 unrelated normal subjects. Except for the fra Xq27, there was no autosomal folate-sensitive fra site significantly more expressed in patients with MBS than in the control group. On the basis of the present cytogenetic sample of about 6 500 R-banded mitoses, a list of all the in vitro folate-sensitive fra sites and their relative frequencies is given.     

Effects of specific monooxygenase and oxidase inhibitors on the activation of 2-aminofluorene by plant cells

Using specific inhibitors, a plant cell/microbe coincubation assay was employed to investigate biochemical mechanisms of plant activation. The biological endpoints of mutation induction, inhibition of mutagenicity and viability of the plant-activating system as well as viability of the microbiological indicator were simultaneously assayed from the same reaction tube. We investigated six inhibitors of monooxygenases and oxidases (diethyldithiocarbamate, methimazole, metyrapone, (+)-catechin, 7,8-benzoflavone and potassium cyanide). The activation of 2-aminofluorene by TX1 cells was mediated by an enzyme system(s) that was inhibited by microM amounts of diethyldithiocarbamate or 7,8-benzoflavone. (+)-Catechin (at low concentrations) or methimazole enhanced the activation of 2-aminofluorene while higher concentrations of (+)-catechin were inhibitory. These data indicate that a significant pathway of the plant activation of 2-aminofluorene is via a cytochrome P-448-type N-hydroxylase. The presence of a FAD-dependent monooxygenase was not detected.     

Plant cells at different stages in their growth curve differentially activate promutagens

Mutagenic activity of the promutagens 2-aminofluorene (2AF) and a contaminant of 4-nitro-o-phenylenediamine (NOP-X) was followed in Ames Salmonella strain TA98 following metabolism by cotton and carrot cell suspension cultures using the plant cell/microbe coincubation assay. Both cell lines were capable of activating each chemical. However, activation capacities of the cell lines differed relative to their respective stage of growth when used. For 2AF activation early-log phase cotton cells and mid-log phase carrot cells proved superior while mid-log phase cotton cells and stationary phase carrot cells proved superior for NOP-X activation. These data indicate that the phase of the growth cycle at which plant cells are harvested can significantly affect their promutagen activation potential.     

Role of environmental factors in autoantibody production - importance of a detailed analysis in a small cohort

In the previous issue of Arthritis Research & Therapy, Muro and colleagues reported a detailed epidemiologic analysis in central Japan on one of the new myositis-specific autoantibodies to MDA-5 (melanoma differentiation-associated gene 5), which is associated with clinically amyopathic dermatomyositis accompanying interstitial lung disease. The increasing prevalence of anti-MDA-5, higher prevalence in small rural towns, and geographical clustering in two areas along the Kiso River suggest a role of environmental factors associated with rural communities or the river/water system or both. A detailed analysis of a small cohort may offer clues, which is ignored in multi-center studies, to the pathogenesis of systemic rheumatic diseases and autoantibody production.     

Automatic sample injector. Its application in the analysis of adenosine triphosphate

The luminescence analysis of ATP requires the rapid and adequate mixing of 10 μliters of low viscosity ATP extract with 100 μliters of viscous luciferin-luciferase preparation. The enzyme-substrate mixture is itself sensitive and will luminesce if excessively agitated. Therefore, mixing must be rapid enough to maximize ATP dependent light emission, but not so vigorous as to cause excitation of the luciferin-luciferase in the absence of ATP. To satisfy this requirement, an automated, pneumatic sample injector was developed and its performance compared to manual injection and to two commercially available mechanical systems. Over a wide range of ATP concentrations (1 × 10^?7 to 1 × 10^?5 μg/μliters) the pneumatic injector demonstrated precision and sensitivity comparable to one of the mechanical injectors and superior to either manual injection or the other mechanical system. In addition, the automated system offered automatic refill, variable injection velocity, volume control, reliability, and ease of operation.