Long-Term Synaptic Changes Induced in the Cerebellar Cortex by Fear Conditioning

AbstractTo better understand learning mechanisms, one needs to study synaptic plasticity induced by behavioral training. Recently, it has been demonstrated that the cerebellum is involved in the consolidation of fear memory. Nevertheless, how the cerebellum contributes to emotional behavior is far from known. In cerebellar slices at 10 min and 24 hr following fear conditioning, we found a long-lasting potentiation of the synapse between parallel fibers and Purkinje cells in vermal lobules V-VI, but not in the climbing fiber synapses. The mechanism is postsynaptic, due to an increased AMPA response. In addition, in hotfoot mice with a primary deficiency of the parallel fiber to Purkinje cell synapse, cued (but not contextual) fear conditioning is affected. We propose that this synapse plays an important role in the learned fear and that its long-term potentiation may represent a contribution to the neural substrate of fear memory

Superior Vena Cava Syndrome in a Patient with Polycytemia Vera: Diagnosis and Treatment

Polycythemia vera is a myeloproliferative disorder characterized by thrombotic complications both in the arterial and venous systems. We report the case of a 55-year-old patient affected by polycythemia vera, presenting with acute superior vena cava syndrome due to thrombosis of the upper part of the superior vena cava. Diagnosis was done clinically and by computed tomography scan and showed an unusual finding: an air bubble trapped in the brachiocephalic venous trunk. The patient underwent emergency surgery. Diagnosis and treatment of the case are discussed

Functional Information, Biomolecular Messages and Complexity of BioSequences and Structures

In the quest for a mathematical measure able to capture and shed light on the dual notions of information and complexity in biosequences, Hazen et al. have introduced the notion of Functional Information (FI for short). It is also the result of earlier considerations and findings by Szostak and Carothers et al. Based on the experiments by Charoters et al., regarding FI in RNA binding activities, we decided to study the relation existing between FI and classic measures of complexity applied on protein-DNA interactions on a genome-wide scale. Using classic complexity measures, i.e, Shannon entropy and Kolmogorov Complexity as both estimated by data compression, we found that FI applied to protein-DNA interactions is genuinely different from them. Such a fact, together with the non-triviality of the biological function considered, contributes to the establishment of FI as a novel and useful measure of biocomplexity. Remarkably, we also found a relationship, on a genome-wide scale, between the redundancy of a genomic region and its ability to interact with a protein. This latter finding justifies even more some principles for the design of motif discovery algorithms. Finally, our experiments bring to light methodological limitations of Linguistic Complexity measures, i.e., a class of measures that is a function of the vocabulary richness of a sequence. Indeed, due to the technology and associated statistical preprocessing procedures used to conduct our studies, i.e., genome-wide ChIP-chip experiments, that class of measures cannot give any statistically significant indication about complexity and function. A serious limitation due to the widespread use of the technology. References J.M. Carothers, S.C. Oestreich, J.H. Davis, and J.W. Szostack. Informational complexity and functional activity of RNA structures. J. AM. CHEM. SOC., 126 (2004), pp. 5130-5137. R.M. Hazen, P.L. Griffin, J.M. Carothers, and J.W. Szostak. Functional Information and the emergence of biocomplexity. Proc. of Nat. Acad. Sci, 104 (2007), pp. 8574-8581. J.W. Szostak. Functional Information: molecular messages, Nature, 423 (2003)

Septic skin lesions: an uncommon manifestation of peripheral prosthetic vascular graft infection

Peripheral prosthetic vascular graft infection following lower limb surgical revascularization is a relatively rare but serious condition. A case of early infection and occlusion of a above-knee femoro-popliteal artery prosthetic bypass is here reported. It was accompanied by acute lower limb ischemia, fever and distally by embolic septic skin lesions