Cortical Modulation of the Transient Visual Response at Thalamic Level: A TMS Study

The transient visual response of feline dorsal lateral geniculate nucleus (dLGN) cells was studied under control conditions and during the application of repetitive transcranial magnetic stimulation at 1 Hz (rTMS@1Hz) on the primary visual cortex (V1). The results show that rTMS@1Hz modulates the firing mode of Y cells, inducing an increase in burst spikes and a decrease in tonic firing. On the other hand, rTMS@1Hz modifies the spatiotemporal characteristics of receptive fields of X cells, inducing a delay and a decrease of the peak response, and a change of the surround/center amplitude ratio of RF profiles. These results indicate that V1 controls the activity of the visual thalamus in a different way in the X and Y pathways, and that this feedback control is consistent with functional roles associated with each cell type

Identification methods in newborn C57BL/6 mice: a developmental and behavioural evaluation

The use of group-housed rodents in many fields of biomedical research imposes a need to identify individuals in a cage. Few studies have been designed to assess possible negative effects of identification methods of newborn mice on their development and wellbeing. In the present study, three different identification methods were applied to newborn C57BL/6J mice on postnatal day (pnd) 5 (toe clipping, toe tattoo ink puncture and subcutaneous implantation of a small transponder). All identification methods used proved to be effective for long-term marking of individual animals. Newborn mice showed the least reaction to toe clipping followed by toe tattoo ink puncture and transponder implantation was the most distressful individual identification procedure in newborn mice. Importantly, clipped toe tissue proved to be enough for genotyping purposes. No overall consistent differences in somatic and neurological reflex development during the postnatal period were shown as a result of the newborn individual identification procedures used. Further, none of the methods interfered significantly with the adult animals' general normal behaviour (e.g. ability to move, grasp, climb) and sensory-motor functions as assessed with a simplified SHIRPA battery of tests, as well as Rotarod and Elevated Plus Maze tests. Postmortem thymus and adrenal gland weights gave no indication of chronic stress as a consequence of the identification method. We conclude that toe clipping might even be advisable in newborn mice at a very young age, when genotyping is needed. Toe tattoo ink puncture is also a good identification method for newborn mice and transponder implantation should only be used in older newborns or applied at weaning.As this study was performed within the framework of the first author’s master thesis, thanks are due to Laboratory Animals Ltd for providing financial support

Increased activation-induced cell death in peripheral lymphocytes of rheumatoid arthritis patients: the mechanism of action

Recently, we have described a soluble survival signal for activated lymphocytes from CD14(+) cells. As a result of the importance of T lymphocytes in the pathogenesis of rheumatoid arthritis (RA), we speculate a possible role for CD14(+) cells in supporting the outgrowth of autoreactive lymphocytes in RA. To address this issue further, supernatants from activated CD14(+) cells (CD14 cocktails) in both normal controls and RA patients were collected. The relative strength of the CD14 cocktails from normal controls and RA patients was compared. The data showed that depletion of CD14(+) cells resulted in a much higher increase of activation-induced cell death (AICD) and a decrease of lymphocyte proliferation in the peripheral blood mononuclear cells of RA patients compared to normal controls. Interestingly, CD14 cocktails from RA patients provide much stronger protection against AICD compared to those from normal controls. The observed soluble survival signal from CD14(+) cells is a general phenomenon because CD14 cocktails prevent both phytohaemagglutinin A-p- and anti-CD3-induced AICD. Furthermore, supernatants collected from human dendritic cell cultures also prevent activated lymphocytes from undergoing AICD. The data implicate an important role of the CD14(+) cell and its secreted form of survival signal in the pathogenesis of RA