Role of neurotensin in radiation-induced hypothermia in rats

The role of neurotensin in radiation-induced hypothermia was examined. Intracerebroventricular (ICV) administration of neurotensin produced dose-dependent hypothermia. Histamine appears to mediate neurotensin-induced hypothermia because the mast cell stabilizer disodium cromoglycate and antihistamines blocked the hypothermic effects of neurotensin. An ICV pretreatment with neurotensin antibody attenuated neurotensin-induced hypothermia, but did not attenuate radiation-induced hypothermia, suggesting that radiation-induced hypothermia was not mediated by neurotensin.     

Sequential Anterograde and Retrograde Conduction Block during Radiofrequency Ablation of an Accessory Pathway

We present an interesting image showing sequential loss of anterograde, and subsequently, retrograde conduction during radiofrequency ablation of an accessory pathway. We discuss the possible mechanisms and prior literature concerning this interesting finding.     

Functional mapping of community‐acquired respiratory distress syndrome (CARDS) toxin of Mycoplasma pneumoniae defines regions with ADP‐ribosyltransferase,vacuolating and receptor‐binding activities

Community‐acquired respiratory distress syndrome (CARDS) toxin from Mycoplasma pneumoniae is a 591‐amino‐acid virulence factor with ADP‐ribosyltransferase (ADPRT) and vacuolating activities. It is expressed at low levels during in vitro growth and at high levels during colonization of the lung. Exposure of experimental animals to purified recombinant CARDS toxin alone is sufficient to recapitulate the cytopathology and inflammatory responses associated with M. pneumoniae infection in humans and animals. Here, by molecular modelling, serial truncations and site‐directed mutagenesis, we show that the N‐terminal region is essential for ADP‐ribosylating activity. Also, by systematic truncation and limited proteolysis experiments we identified a portion of the C‐terminal region that mediates toxin binding to mammalian cell surfaces and subsequent internalization. In addition, the C‐terminal region alone induces vacuolization in a manner similar to full‐length toxin. Together, these data suggest that CARDS toxin has a unique architecture with functionally separable N‐terminal and C‐terminal domains.     

Global Expression Analysis of the Yeast Lachancea (Saccharomyces) kluyveri Reveals New URC Genes Involved in Pyrimidine Catabolism

Pyrimidines are important nucleic acid precursors which are constantly synthesized, degraded, and rebuilt in the cell. Four degradation pathways, two of which are found in eukaryotes, have been described. One of them, the URC pathway, has been initially discovered in our laboratory in the yeast Lachancea kluyveri. Here, we present the global changes in gene expression in L. kluyveri in response to different nitrogen sources, including uracil, uridine, dihydrouracil, and ammonia. The expression pattern of the known URC genes, URC1-6, helped to identify nine putative novel URC genes with a similar expression pattern. The microarray analysis provided evidence that both the URC and PYD genes are under nitrogen catabolite repression in L. kluyveri and are induced by uracil or dihydrouracil, respectively. We determined the function of URC8, which was found to catalyze the reduction of malonate semialdehyde to 3-hydroxypropionate, the final degradation product of the pathway. The other eight genes studied were all putative permeases. Our analysis of double deletion strains showed that the L. kluyveri Fui1p protein transported uridine, just like its homolog in Saccharomyces cerevisiae, but we demonstrated that is was not the only uridine transporter in L. kluyveri. We also showed that the L. kluyveri homologs of DUR3 and FUR4 do not have the same function that they have in S. cerevisiae, where they transport urea and uracil, respectively. In L. kluyveri, both of these deletion strains grew normally on uracil and urea.