Delayed hypersensitivity in mice induced by intravenous sensitization with sheep erythrocytes: evidence for tuberculin type delayed hypersensitivity of the reaction

Delayed hypersensitivity (DH) reaction can be induced in mice by intravenous sensitization with sheep erythrocytes (SRBC). However, as the sensitizing procedure is quite different from a usual mode of sensitization for DH using complete Freund's adjuvant (FCA), the nature of this reaction has been a matter of controversy. In an attempt to characterize this reaction, we placed special interest on two possibilities regarding the nature of this reaction; Jones-Mote reaction or tuberculin type DH. From the kinetics study on the DH after challenge, the DH reaction to SRBC in mice by intravenous sensitization was clearly distinguished from the Arthus reaction. The dose-response pattern of this reaction also suggested that the contribution of Arthus reactivity to delayed reactivity was negligible. Cell reconstitution experiments revealed this DH to be quantitatively thymus cell dependent. Furthermore, this DH required macrophages at its manifestation stage, and appearance of basophil infiltration at the lesion was absent. In addition, strain difference and ageing of host mice influenced the DH reaction in exactly the same fashion in which these factors influence the tuberculin type-DH induced by subcutaneous sensitization with methylated human serum albumin (MHSA) in FCA. Taken collectively, it was concluded that this DH reaction can be categorized as the tuberculin type.

Studies on composites of collagen and a synthetic polymer. Second report - mode of reaction of a laminar composite with living tissue, and results of long-term implantation

We have been studying composites of synthetic polymers and proctase-treated bovine collagen (telopeptide-poor collagen). In a previous paper, it is described that one of our composites appears to have a high tissue affinity, because it was found under a scanning electron microscope, well bonding the living tissue 6 weeks after implantation in the rabbit subcutaneous tissue. In the present study, the composites were also implanted in the subcutaneous tissue in rabbits to observe the mode of its bonding to the living tissue, and at the same time the bonding force was measured at various intervals during a period of 1.5 years, to observe the degree and duration of the effect of the composition, and further to study the optimal conditions for preparation of such a composite. As a method of composition, ultraviolet radiation and glutaraldehyde treatment were also comparatively examined, besides gamma-radiation that had been employed in a previous study. As the results, it is revealed that the composite bonds to the living tissue in such a manner that a portion of the collagen part is digested and absorbed to be replaced by the invading connective tissue and a part of collagen near the surface of the synthetic polymers had escaped digestion to combine with the rabbit's own collagen fiber. From these results we like to insist that the mode of reaction of our composites may be similar to real organization and be different in natur from mere encapsulation which was shown by the artificial materials hitherto in use to be considered to have a good tissue affinity. Therefor we think now the encapsulation is pseudoorganization. It is also shown that the bonding force of the composite to the living tissue and its duration depend chiefly on the degree of swelling, that is, the degree of intermolecular cross-linking, of the composed collagen part. Out of the gamma-radiated composites, those radiated 1--3 Mrads proved desirable in both tissue affinity and duration of tissue bonding, with a potent bonding force remaining effective even 1.5 years later, while the composite radiated with 5 Mrads or more proved poorer in these properties because of destruction of the collagen part, vastly varying in the properties. By ultraviolet radiation, it was easy to control the degree of swelling of collagen part with the radiation dose, however, this method gave a lower bonding force and a shorter duration of the force than gamma-radiation. The glutaraldehyde method allowed the collagen to remain over a long time, but gave the composite less tissue affinity than the other two methods.

Studies on copolymers of collagen and a synthetic polymer. First report--experimental study on biocompatibility of laminar copolymers of collagen and a synthetic polymer

To develop biomaterials for semiparmanent substitution, we are studying copolymers of collagen and a synthetic polymer. In this study, in order to test tissue compatibility, the laminar copolymers were prepared from bovine collagen treated with proctase to remove telopeptides and synthetic polymers such as polyethylene, polyvinylalcohol, silicon gum etc., by the OKAMURA-HINO metthod, namely polymerization achieved by the introduction of cross-lincages, applying plasma discharge and gamma-irradiation. These copolymers were implanted into dorsal subcutaneous tissue in rabbits and removed after 1, 2, 3, 4 and 6 weeks to be examined by light microscope and electron microscope. One or two weeks after implantation, we observed that a large number of fibroblasts gathered on the surface of the grafted collagen. After 3 or 4 weeks, bridges of collagen fibrils were observed between the copolymers and rabbit tissue. These copolymers were firmly adhered to the tissues and separable only with difficulty. These results showed that the copolymers maintain the capacity for extreme strong bonding for at least 6 weeks and possess high tissue compatibility. From that we concluded copolymers are useful as a biomedical material.

A cooperative study of sarcoidosis in Asia and Africa: descriptive epidemiology

An eight-nation cooperative epidemiological study revealed the Asian and African features of sarcoidosis. Almost every country reported from several to less than 30 cases, except for Japan which had already collected over 3,000 cases. Not a single case was found in the mass x-ray surveys conducted by several countries on a large scale (Tables 1 and 2). Although the number of the cases included in this study were small, this information is the first of this kind for Asia and Africa.