THE PURIFICATION AND CONCENTRATION OF DIPHTHERIA TOXOID

By precipitation with acetone at 4°C. a refined diphtheria toxoid was obtained as a dry powder, readily soluble in aqueous solutions. The powder itself appears to be stable. When dissolved in half the original volume of physiological salt solution, the toxoid remained stable, in the cold room, for a period of 7 months. Only toxoids should be used which have been completely detoxified by the treatment with formalin. The formalin is immediately and completely removed by precipitation with acetone. Filtration through a Mandler filter or the addition of a preservative did not appear to have any deleterious effect. Incubating at 39°C. and freezing for 20 hours did not impair its activities. The flocculating value of the purified toxoid containing phenol was almost completely destroyed by freezing, while when merthiolate was the preservative, it was unchanged. Approximately 62 per cent of the nitrogen was eliminated in the process with approximately 15 per cent loss in flocculating value. The flocculating values were nearly double those of the original material and thus corresponded with the concentration, which was onehalf the volume. By this method, the antigenic activity of a toxoid below standard may be increased to a satisfactory standard. The antigenic activity of the refined product in the immunization of guinea pigs may in general parallel its flocculating values but the relation between the results of these tests may not be proportional nor constant. As an immunizing agent in the guinea pig, the refined toxoid possesses an antigenic activity that is equal to, or greater than, that of the unconcentrated toxoid.     

PURIFICATION AND CONCENTRATION OF ANTIGENS FOR COMPLEMENT FIXATION BY METHODS OF DIALYSIS,ADSORPTION, AND EXTRACTION

Antigens were prepared from the culture filtrates of tubercle bacilli and by extraction of washed and dried organisms with organic and aqueous solvents and from tissues of organs showing tuberculous lesions. A comparison of these preparations by means of the complement fixation test showed that the aqueous extracts were most active antigenically. The antigenic activity of the aqueous preparations and also of the slightly active culture filtrates was increased by means of dialysis and adsorption with serum globulin followed by extraction with alcohol and concentration of the alcoholic extract in vacuo.     

Origin and selection of peripheral CD4-CD8- T cells bearing alpha/beta T cell antigen receptors in autoimmune gld mice

We have analyzed the origin and development of unusual CD4-CD8- alpha/beta T cell receptor-positive peripheral T cells produced in large numbers by mice homozygous for the gld mutation (C3H-gld/gld). These mice may be an important model for investigating processes controlling T cell development. Bone marrow transfers demonstrated that the gld defect was intrinsic to bone marrow-derived cells. Clonal deletion of potentially autoreactive cells was observed in peripheral gld CD4-CD8-, CD4+CD8-, and CD4-CD8+ T cells, as well as mature thymocytes. This suggests that gld CD4-CD8- T cells have passed through the thymus in ontogeny and that gld autoimmunity does not result from a general defect in elimination of self-reactive thymocytes. These observations, combined with demethylation of the CD8 gene in the CD4-CD8- population, support prior expression of CD4 and/or CD8 in gld CD4-CD8- T cell ontogeny, perhaps at a CD4+CD8+ stage. Steroid sensitivity of gld thymocytes and CD4-CD8- T cells was normal. Therefore, we found no gross abnormalities in two major mechanisms of inducible cell death in the gld thymus, the clonal deletion process associated with tolerance and the steroid-inducible endogenous endonuclease thought to be involved in apoptosis of unselected thymocytes. The data suggest that if gld CD4-CD8- T cells arise via escape from normal elimination in the thymus, they must do so by a novel defect in thymic selection (perhaps related to aberrant positive signals) and/or are expanded by an extrathymic process which allows clonal deletion to occur.     

Die Regeneration des Hornhautepithels

Ohne ZusammenfassungHierzu Taf. III–IV.     

Intrarater reliability of manual muscle testing and hand-held dynametric muscle testing

Physical therapists require an accurate, reliable method for measuring muscle strength. They often use manual muscle testing or hand-held dynametric muscle testing (DMT), but few studies document the reliability of MMT or compare the reliability of the two types of testing. We designed this study to determine the intrarater reliability of MMT and DMT. A physical therapist performed manual and dynametric strength tests of the same five muscle groups on 11 patients and then repeated the tests two days later. The correlation coefficients were high and significantly different from zero for four muscle groups tested dynametrically and for two muscle groups tested manually. The test-retest reliability coefficients for two muscle groups tested manually could not be calculated because the values between subjects were identical. We concluded that both MMT and DMT are reliable testing methods, given the conditions described in this study. Both testing methods have specific applications and limitations, which we discuss.