Interaction of anaesthetics with electrical synapses

Studies of the interaction of anaesthetics with various preparations, from whole animals to organic solvents, have been continuing since Overton and Meyer found a correlation between anaesthetic potency and solubility in olive oil. Although the physiological basis of anaesthesia is far from clear, one popular hypothesis is that anaesthetics act primarily by interfering with the normal functioning of chemical synapses. This hypothesis is supported by experiments showing that these synapses are more sensitive to both local and general anaesthetics than are axons. The effects of anaesthetics on electrical synapses (gap-junctions or nexus) have not previously been studied. These ubiquitous structures, presumably responsible for cell-to-cell communication, are found in most vertebrate and invertebrate tissues. We report here the effects of several anaesthetics on electronic coupling between nerve cells, and show that electrical synapses are less sensitive to most anaesthetics than are chemical synapses and axonal membranes.     

Molecular cloning of lymphadenopathy-associated virus

Lymphadenopathy-associated virus (LAV) is a human retrovirus first isolated from a homosexual patient with lymphadenopathy syndrome, frequently a prodrome or a benign form of acquired immune deficiency syndrome (AIDS). Other LAV isolates have subsequently been recovered from patients with AIDS or pre-AIDS and all available data are consistent with the virus being the causative agent of AIDS. The virus is propagated on activated T lymphocytes and has a tropism for the T-cell subset OKT4 (ref. 6), in which it induces a cytopathic effect. The major core protein of LAV is antigenically unrelated to other known retroviral antigens. LAV-like viruses have more recently been independently isolated from patients with AIDS and pre-AIDS. These viruses, called human T-cell leukaemia/lymphoma virus type III (HTLV-III) and AIDS-associated retrovirus (ARV), seem to have many characteristics in common with LAV and probably represent independent isolates of the LAV prototype. We have sought to characterize LAV by the molecular cloning of its genome. A cloned LAV complementary DNA was used to screen a library of recombinant phages constructed from the genomic DNA of LAV-infected T lymphocytes. Two families of clones were characterized which differ in a restriction site. The viral genome is longer than any other human retroviral genome (9.1-9.2 kilobases).     

Effects of lesions of the anterior raphe nuclei on the self-administration of d-amphetamine in the rat : considerable increase of desire for the poison

The acquisition of the intravenous self-administration of d-amphetamine was studied after separate lesions of anterior raphe nuclei (dorsal or median). Every lever-press delivered 2.5 microliter of a d-amphetamine solution dosed at 7.5 microgram/kg. Lesion of anterior raphe nuclei produced an hyper-sensitivity to d-amphetamine as indicated by a dramatic increase in self-administration by experimental Rats compared to the controls. Moreover this enhanced self-administration behavior is observed with a low blood concentration of d-amphetamine. The greater increase was obtained for median raphe lesioned Rats. These effects are interpreted in terms of 5HT-DA balance and could provide an experimental model for neurobiological bases of drug addiction studies.     

The effect of mouse erythrocyte rosette forming lymphocytes on lymphokine production in T-cell cultures

Summary An enhancement effect of mouse erythrocyte rosette forming (MERF) cells on the production of migration inhibitory factor, chemotactic factor for neutrophils and skin reactive factor in T-lymphocyte cultures stimulated with the purified protein derivative of tuberculin was observed. We consider it likely that the MERF cells, possessing the appropriate cell surface constituents to construct an immunogenic moiety, present antigen on their surfaces to elicit lymphokine production.This work was supported by the Scientific Research Council, Ministry of Health, Hungary, Code No. 421030401 1/s     

A soft solid surface on Titan as revealed by the Huygens Surface Science Package

The surface of Saturn's largest satellite--Titan--is largely obscured by an optically thick atmospheric haze, and so its nature has been the subject of considerable speculation and discussion. The Huygens probe entered Titan's atmosphere on 14 January 2005 and descended to the surface using a parachute system. Here we report measurements made just above and on the surface of Titan by the Huygens Surface Science Package. Acoustic sounding over the last 90 m above the surface reveals a relatively smooth, but not completely flat, surface surrounding the landing site. Penetrometry and accelerometry measurements during the probe impact event reveal that the surface was neither hard (like solid ice) nor very compressible (like a blanket of fluffy aerosol); rather, the Huygens probe landed on a relatively soft solid surface whose properties are analogous to wet clay, lightly packed snow and wet or dry sand. The probe settled gradually by a few millimetres after landing.