In vitro analysis of immune responses of inbred guinea pigs infected in vivo with Leishmania enriettii and an investigation of active immunization of susceptible animals

Adherent skin cell monolayers have been prepared from the infected area of inbred guinea pigs inoculated with Leishmania enrietti. Cells from those animals most susceptible to disease (2/N) are less able to promote proliferation and the production of macrophage migration inhibition factor (MIF) from leishmania-immune lymphocytes than are infected cells taken from the more resistant 13/N or (2/N × 13/N)F₁ animals. Exposure of immune lymphocytes of all strains to parasite antigen in the relative absence of autologous antigen-presenting cells induced the development of a suppressor pool capable of inhibiting lymphocyte proliferation in response to immunogenic signals. Decreased lymphocyte proliferation during the course of disease may be caused by the endogenous release of products of arachidonic acid metabolism from host monocytes, though along with the decline in DTH reactivity in infected animals, and apparently in concert with the healing of the primary lesion, there occurs an increase in titer of antileishmania antibody in infected animals. Preliminary attempts to confer protection of naive animals by preimmunization with lymphocytes from previously infected, susceptible, or resistant guinea pigs suggested a role for interacting “helper” and suppressor lymphocyte pools in the immunoprotection from leishmania infection.     

Ultraviolet light modification of the prostaglandin receptor

Prostaglandin E₁ elicits minimal inhibition of ultraviolet lightinduced platelet aggregation. Exposure to ultraviolet light progressively inhibits prostaglandin-induced responses in both the ADP-aggregating platelet and in uterine smooth muscle. This effect, which is cumulative and lasting, may be prevented or fully reversed by a sulfhydryl-oxidizing agent. Ultraviolet light may, therefore, initiate reduction of critical disulfide groups in the vicinity of the prostaglandin receptor. The technique of ultraviolet irradiation may serve as a useful tool in the specific determination of prostaglandins in biological systems.     

The face is not an empty canvas: how facial expressions interact with facial appearance

Faces are not simply blank canvases upon which facial expressions write their emotional messages. In fact, facial appearance and facial movement are both important social signalling systems in their own right. We here provide multiple lines of evidence for the notion that the social signals derived from facial appearance on the one hand and facial movement on the other interact in a complex manner, sometimes reinforcing and sometimes contradicting one another. Faces provide information on who a person is. Sex, age, ethnicity, personality and other characteristics that can define a person and the social group the person belongs to can all be derived from the face alone. The present article argues that faces interact with the perception of emotion expressions because this information informs a decoder''s expectations regarding an expresser''s probable emotional reactions. Facial appearance also interacts more directly with the interpretation of facial movement because some of the features that are used to derive personality or sex information are also features that closely resemble certain emotional expressions, thereby enhancing or diluting the perceived strength of particular expressions.