Drug susceptibility of PCA in WBB6F1-W/Wv mice

Our previous study revealed that passive cutaneous anaphylaxis (PCA) can be produced in congenitally mast cell-deficient WBB6F1-W/W^v (abbreviated as W/W^v) mice on sensitization with undiluted or slightly diluted allogeneic and xenogeneic antisera but not on sensitization with allogeneic monoclonal immunoglobulin (Ig)E and IgG1 antibodies regardless of the antibody concentration [1]. In view of these findings, the present study was conducted to characterize PCA in this strain from its drug susceptibilities using mast cell-bearing WBB6F1-+/+ (abbreviated as +/+) and B6D2F1 mice as references. PCA in W/W^v mice mediated by a low dilution (1  4) of hyperimmune serum to bovine serum albumin of the B6D2F1 mouse origin was markedly suppressed by CV-6209, an antagonist of platelet-activating factor (PAF), but not by antihistamines such as cyproheptadine and oxatomide. In contrast, PCA in +/+ and B6D2F1 mice mediated by a high dilution (1  128) of the anti-serum (virtually by IgG1 antibody) was nearly completely suppressed by antihistamines but not by CV-6209. A remarkable difference between PCA in W/W^v and reference mice was also observed in the susceptibility to monoclonal anti mouse granulocyte (Gr-1) antibody PCA in W/W^v mice was potently suppressed by the 1- to 3-day pretreatment with this antibody but that in references was not at all. Putting these present results together with the previous finding that anti-granulocyte antibody greatly reduces circulatory Gr-1⁺ leukocytes, 1 to 3 days after the treatment [2], it is highly probable that PCA in W/W^v mice mediated by some antibody isotypes other than IgE and IgG1 is produced by PAF mainly released from Gr-1⁺ cells, while IgG1 antibody-mediated PCA in mast cell-bearing reference mice is evoked by histamine derived from mast cells. PCA homologous to that in W/W^v mice could also be produced in the reference mice on sensitization with undiluted or slightly diluted antiserum, when generalized blueing due to excess IgG1 antibody was removed by the oxatomide treatment be fore the antigen challenge. Received 10 December 1997; received after revision 2 February 1998; accepted 23 February 1998     

Presence of anti-Trypanosoma cruzi antibodies in the sera of mice with experimental autoimmune myocarditis

Summary The existence of antigens shared in common byT. cruzi and heart muscle cells is suggested by the presence of antibodies binding to the parasite surface in the serum of mice with autoimmune myocarditis induced by immunization with syngeneic heart antigens.     

Presence of anti-Trypanosoma cruzi antibodies in the sera of mice with experimental autoimmune myocarditis.

The existence of antigens shared in common by T. cruzi and heart muscle cells is suggested by the presence of antibodies binding to the parasite surface in the serum of mice with autoimmune myocarditis induced by immunization with syngenic heart antigens.     

Comparison of the inhibitory activity and concentration of alfa1-antiprotease in normal human sera

Summary Inhibitory activity and concentration of alfa₁-antiprotease were simultaneously determined in sera of 80 blood donors. The lack of the coincidence of these 2 parameters was observed in about half the subjects tested.This work was supported in part by the Polish Academy of Sciences — PAN 337/VI.     

NMR structures of the C-terminal end of human complement serine protease C1s

Synthetic peptides derived from the C-terminal end of the human complement serine protease C1s were analysed by circular dichroism and nuclear magnetic resonance (NMR) spectroscopy. Circular dichroism indicates that peptides 656-673 and 653-673 are essentially unstructured in water and undergo a coil-to-helix transition in the presence of increasing concentrations of trifluoroethanol. Two-dimensional NMR analyses performed in water/trifluoroethanol solutions provide evidence for the occurrence of a regular α-helix extending from Trp659 to Ser668 (peptide 656-673), and from Tyr656 to Ser668 (peptide 653-673), the C-terminal segment of both peptides remaining unstructured under the conditions used. Based on these and other observations, we propose that the serine protease domain of C1s ends in a 13-residue α-helix (656Tyr-Ser668) followed by a five-residue C-terminal extension. The latter appears to be flexible and is probably locked within C1s through a salt bridge involving Glu672. Received 19 November 1997; accepted 24 November 1997     

Effect of adaptation level on maintained firing and sensitivity in receptive field center of X and Y cells

Summary Maintained firing rates of X cells and Y cells were compared at 6 adaptation levels (AL) between –2.71 log cd/m² and 2.28 log cd/m² (10 mm² pupil size). X cell maintained firing was higher at all ALs and was statistically different at medium and high ones. Changes in AL had nearly identical effects upon X and Y cell suprathreshold sensitivity to a flashing spot in the center of their receptive fields; the Weber function had a slope of 0.744 for Y cells and 0.743 for X cells. These values are not statistically different.This research is supported by Public Health Service grant no. EY 00701.     

Effect of adaptation level on maintained firing and sensitivity in receptive field center of X and Y cells

Maintained firing rates of X cells and Y cells were compared at 6 adaptation levels (AL) between -2.71 log cd/m2 and 2.28 log cd/m2 (10 mm2 pupil size). X cell maintained firing was higher at all ALs and was statistically different at medium and high ones. Changes in AL had nearly identical effects upon X and Y cell suprathreshold sensitivity to a flashing spot in the center of their receptive fields; the Weber function had a slope of 0.744 for Y cells and 0.743 for X cells. These values are not statistically different.     

Intrinsic fluorescence of mitochondrial F1-ATPase

Summary The emission maximum of the fluorescence spectrum of the mitochondrial F₁-ATPase in shifted from 305 to 334 nm when the excitation wavelength is altered from 270 to 300 nm. This indicates that both tyrosine and tryptophan contribute to the intrinsic fluorescence of the F₁-ATPase.Acknowledgments. The authors wish to thank F. Penin for his preparation of F₁-ATPase and Drs J. M. Jallon and N. Gains for their stimulating discussions. This research was supported by the CNRS and by the DGRST (contract 77-7-0277).     

The murine complement regulator Crry: new insights into the immunobiology of complement regulation

Complement has an important role in inflammation and in the normal function of the immune system. Activated complement fragments have the capacity to bind and damage self-tissues. Cells from vertebrates express on their surface regulators of complement activation that protect them from the deleterious effects of cell-bound complement fragments. Abnormalities in these regulators of complement activation may participate in the pathogenesis of autoimmune diseases and inflammatory disorders. Murine Crry is one of these regulators that inhibits the activation of the third component of complement and protects self-tissues from complement-mediated damage. Experimental work on Crry has increased our understanding of the immunobiology of complement regulation and the potential role of complement and complement inhibitors in the development and treatment of human diseases. Received 13 June 2001; received after revision 12 July 2001; accepted 9 August 2001     

Intrinsic fluorescence of mitochondrial F1-ATPase.

The emission maximum of the fluorescence spectrum of mitochondrial F1-ATPase is shifted from 305 to 334 nm when the excitation wavelength is altered from 270 to 300 nm. This indicates that both tyrosine and tryptophan contribute to the intrinsic fluorescence of the F1-ATPase.     

Trial selection of 2 sub-strains of NZB mice based on the level of chromosome aberrations]

Increased chromosomal breakage is observed in NZB mice. Breeding experiments with mice selected according to breakage frequencies provide evidence that the proportion of animals with high and low breakage figures in the first and second generation progeny depends on the phenotype of the parents.