Release of platelet-activating factor (PAF-acether) from alveolar macrophages by the calcium ionophore A 23187 and phagocytosis

Platelet-activating factor (PAF-acether) was recovered from rabbit, rat and human alveolar macrophages stimulated with the Ca++ ionophore A23187. PAF-acether release was also obtained from rat and rabbit macrophages in the presence of zymosan, but not from human alveolar preparations in spite of the phagocytic activity exhibited by the latter cells. Observed releases were active, Ca++ dependent, and plateaued at 45 min. No PAF-acether was released from lungs washed out of their macrophages, another argument against the mastocyte origin of this mediator. Given the potent bronchoconstrictive activity of PAF-acether, its release from alveolar macrophages may provide an alternative explanation for non IgE-dependent asthmas and the implication of platelets in pulmonary diseases.     

In Vivo Immunosuppressive Effects of Recombinant Ovine Interferon-tau (Trophoblastin): r.oTP (r.oIFN-τ) Inhibits Local GVH Reaction in Mice (PLN Assay), Prevents Fetal Resorptions,and Favors Embryo Survival and Implantation in the CBA/J × DBA/2 Mice Combination

PROBLEM : Ovine trophoblastin protein, be it natural or recombinant (oTP, r.oTP), a member of the tau interferon family (r.oIFN-τ), has been shown to possess immunosuppressive properties in vitro. It acts as a cytostatic agent across species. Indeed, it was immunosuppressive when tested on human and murine lymphocytes in a variety of in vitro immune assays, as it is also on syngenic (ovine) lymphocytes. METHODS : In the present paper, we first verified that this property to act across species also occurred in vivo assays; r.oTP was able to down regulate a local GVH reaction assay (PLN assay) in mice. We then took advantage of these properties of r.oTP to investigate its in vivo effects during murine pregnancy as there is no ovine equivalent of the murine CBA/ J × DBA/2 resorption prone mating combination. RESULTS : When given in the postimplantation period, r.oTP drastically boosted resorptions in the CBA/J × DBA/2 matings, as did murine recombinant gamma interferon. However, the same r.oTP treatment in the peri-implantation period resulted in a reduction in resorptions in this spontaneous abortion system. CONCLUSION : The data suggested that r.oTP might have acted more by favouring implantation and embryo survival than by preventing the resorption process itself. The mechanisms possibly underlying these effects, as well as the putative uses of r.oTP evolving from these data, are discussed.     

Relationship Between Different Recovery Curves Representing Rate-Dependent AV Nodal Function in Rabbit Heart

Nodal Function and Recovery Measures. Introduction: The rate-dependent changes in atrioventricular (AV) nodal conduction time show different characteristics depending upon whether the conduction times are plotted against the atrial interval (AA-recovery curve) or His-atrial interval (HA-recovery curve). This study characterizes these differences in the context of controlled changes of nodal functional properties, determines their functional significance, and tests the hypothesis that they are related solely to the nodal conduction time of the last beat (last conduction time) before the premature beat.
Methods and Results; Premature nodal conduction times obtained in isolated rabbit heart preparations under various steady-state and transient conditions were plotted as a function of the corresponding HA and AA intervals, as well as the AA interval corrected for the last conduction time. Under all conditions, the corrected AA-recovery curve was indistinguishable in shape from the HA-recovery curve, and as such reflected similar underlying nodal functional properties. Moreover, a selective increase in the last conduction time, induced in the absence of time-dependent effects associated with the functional property of fatigue, shifted the AA-recovery but not the HA-recovery curve upward with respect to the control curve.
Conclusion: The last conduction time accounts entirely for differences between AA-recovery and HA-recovery curves that otherwise reflect the same underlying nodal functional state. Thus, a consistent assessment of rate-dependent changes in nodal function can be achieved with either measure of recovery time.     

Medical ethics in prison

This paper describes the medical services at Champ-Dollon Remand Prison in Geneva, and raises issues which relate to the consent of patients and the independence of doctors. A series of situations are presented, describing the relations of prison doctors with administrative and judicial authorities, and with the patients themselves. Prison medicine provides useful examples for the teaching of medical ethics.