Studies on antigen-induced arthritis in mice. II. Immunologic correlates of arthritis susceptibility in mice.

Antigen-induced arthritis was developed in mice as a model of human rheumatoid arthritis by using methylated bovine serum albumin (mBSA) as antigen. It was found that most strains were susceptible, whereas CBA mice were resistant. We therefore investigated the humoral and cell-mediated immune responses to mBSA in resistant mice (CBA) and susceptible mice (exemplified by C57BL) to determine whether these were associated with susceptibility to arthritis. The resistant strain (CBA) differed from the suceptible strains in the following respects. First, there was a lower humoral immune response to mBSA as measured by passive hemagglutination, but this could be overcome by a larger immunogenic dose. Secondly, there were differences in response to low doses of DNP-mBSA after mBSA carrier preimmunization. Thirdly, there were striking differences in delayed-type hypersensitivity (DTH) to mBSA as determined by a radioisotopic assay in vivo; the response of CBA mice occurred early, at 5 days, declined quickly, and was weaker, whereas that of C57BL mice developed later and was long sustained. Genetic studies of the DTH response with hybrids and backcrosses showed an oligogenic control of immune responsiveness, with one gene being linked to the H-2b allele of the susceptible C57BL mice, and another being independent of the H-2 complex. Our findings indicate that in mice, susceptibility to antigen-induced arthritis with mBSA correlates with a higher responder state to this antigen, and that T cells are the major if not the only determinant of the high responder state.     

Oxygen participation in the in vivo and in vitro aging of collagen fibres

We have examined, as a function of oxygen concentration, the in vivo and in vitro aging rates of tendon from animal species with widely differing life-spans. The results suggest that concomitant with the genetically determined aldimine type cross-linking reactions which probably are complete by the time the animal has reached physiological maturity, there is an on-going oxygen-mediated system of reactions which also effectively cross-link the structure. These reactions appear to proceed with their own intrinsic rate dependent only upon oxygen concentration, and independent of the particular species involved. They may not be required by connective tissues, but are an unavoidable consequence of the presence of free oxygen in tissues with a low rate of turnover.     

Influence of substituent ribose on transition state affinity in reactions catalyzed by adenosine deaminase

Adenosine deaminase from calf intestine hydrolyzes adenine at a limiting rate four orders of magnitude lower than that for adenosine, while Km values for these substrates are about the same (Wolfenden, R., et al. (1969), Biochemistry 8, 2412-2415). Reactivity of 6-substituents, toward nucleophilic displacement, is found to be affected only slightly by removal of ribose as a 9-substituent, in model reactions. Substituent ribose thus appears to stabilize, selectively, the transition state for enzymatic deamination. In contrast with the small influence of substituent ribose on the apparent binding affinity of substrates, removal of substituent ribose from a potential transition state analogue, 1,6-dihydro-6-hydroxy-methylpurine ribonucleoside, results in a lowering of its affinity for the enzyme by several orders of magnitude. The synthesis of the analogue and related compounds is described, and their properties compared with those of other photoadducts and of the naturally occurring inhibitors covidarabine and coformycin. Binding of these inhibitors is found to result in the appearance of ultraviolet-absorbing bands in the neighborhood of 323 nm.     

Optimal conditions for lactoperoxidase catalyzed radioiodination of external proteins on mouse erythrocytes

Optimal conditions were established for specific labelling of the surface proteins of mouse erythrocytes using lactoperoxidase-catalyzed radioiodination. The levels of H2O2 and I-, and cell concentrations required for restriction of haemoglobin labelling to less than 5% of the total 125I-protein, were different for radioiodination employing direct H2O2 addition or generation of H2O2 with glucose oxidase plus glucose. Preparation of mouse erythrocyte ghosts by hypotonic lysis caused loss of some minor labelled proteins present on intact cells and shifts to lower molecular weights of others. It is therefore important to solubilize labelled cells directly in electrophoresis buffer to avoid artifactual degradation of labelled proteins. The extent of labelling internal cell proteins was measured by a procedure suitable for the comparison of a large number of samples: solubilized radioiodinated erythrocytes were electrophoresed on 14% acrylamide gels and the radioactivity determined in the haemoglobin band which migrates separately from other proteins. The major labelled protein on the mouse erythrocytes had an apparent molecular weight of 92,000, and may be analogous to Band 3 of the human erythrocyte.     

Sequential principal components analysis,a tool for cluster detection in large bacteriophage-typing data samples

Using, as an example, the susceptibility of 437 bacterial strains (belonging to nomenspecies of the genera,Pseudomonas andXanthomonas) to 86 bacteriophage preparations, this study describes how sequential removal of the more distinctive emerging clusters (or selected groups of elements with prior knowledge of their taxonomic relationships) in a principal components analysis can be employed to analyze, the affinities among the remaining original numerical units. The initial, well-defined clusters had a constraining impact on other elements. This constraint was eased upon successive removal from the data matrix of initially distinctive clusters, thereby enabling clearer views of the relationships among the remaining elements. This procedure (sequential principal components analysis) might be used to evaluate the impacts of individual taxa in a numerical classification.     

The composition of intracellular granules from the metal-accumulating cells of the common garden snail (Helix aspersa).

Certain cells in the hepatopancreas of the common garden snail (Helix aspersa) contain intracellular granules that are sites of metal-ion accumulation. These granules have been extracted and investigated by u.v. and i.r. spectroscopy, atomic-absorption spectroscopy, X-ray microanalysis, thermogravimetric analysis, enzymic assay and microanalysis. The deposits contain about 18% (w/w) water, 5% (w/w) organic matter and 76% (w/w) inorganic material of which the main components are Ca2+, Mg2+ and P2O7(4)-. The possible origin of these granules is discussed, as is their role in detoxifying heavy-metal ions.