A. A. Ukhtomskii and the reflex theory of behavior

There can be no doubt whatsoever that Russian physiology has brought to international science vital new findings in the study of reflexes, A. A. Ukhotomskii (Collected Works, Vol. 6, p. 142).Translated from Zhrunal Vysshei Nervnoi Deyatel'nosti imeni I. P. Pavlova, Vol. 35, No. 3, pp. 403–412, May–June, 1985.     

Hepatitis A. Perspectives and recent advances.

The basis for the epidemiologic and etiologic differentiation of two major forms of viral hepatitis, hepatitis A and B, was established in a series of studies undertaken between 1930 and 1970. Final recovery and visualization of the presumed etiologic agent of hepatitis A was not, however, accomplished until the technique of immune electron microscopy was applied to the examination of specimen materials collected from individuals in the early acute stages of infection. Morphologically homogeneous virus-like particles of 27 nm diameter have now been recovered from stools of patients with hepatitis A ill from a variety of sources. Antibody to these particles has been shown to develop during the course of infection with hepatitis A but not with hepatitis B and disease has been induced in nonhuman primates inoculated with purified particle containing fractions. The classification of hepatitis A virus has not been conclusively established, but it would appear to be either a parvovirus or an enterovirus.     

Cyclosporin A and the thymus. Immunopathology.

Cyclosporin A (CsA) is known to diminish the size of the thymus, especially the thymic medulla. The significance of these changes is not presently understood. This study reveals several immunopathologic changes induced in the thymic medulla by CsA (15 mg/kg/day). The weight and relative size of the thymus dramatically and rapidly involutes, with marked changes observed in 1 week. The medullary thymocytes show segregation of rat T-cell phenotypes as seen in control rats, but the number of such cells is markedly reduced in accordance with the medullary remnant. This is consistent with a maturational arrest of thymocytes. The medullary epithelium was assessed directly by irradiating the control or CsA-treated rats 2 days prior to sacrifice. The epithelium of Hassall's corpuscles was essentially absent in CsA-treated rats but prominent in control rats. The cortical epithelial cells were preserved. Stains for Ia antigen with the anti-OX4 antibody show little change in expression by cortical epithelium, but a marked reduction in the Ia+ medullary cells in the thymocyte purged rats. All of these changes were reversible in the normal rat after cessation of CsA, with near normal recovery in 3 weeks. No morphologic or immunopathologic changes were noted in the cortical thymocytes. These cells did, however, acquire CsA receptors, as detected by the binding of fluorescent dansylated CsA.