Trichobezoars in children: therapeutic complications.

Trichobezoars are concretions formed by the accumulation of hair or fibers in the gastrointestinal tract, usually associated with underlying psychiatric disorders in females between 13 and 20 years old. Endoscopy, the gold standard for diagnosis, brings some additional advantages: sample taking, size reducing and, rarely, mass removal. This study shows that endoscopy can cause severe complications resulting in a surgical emergency.

Pin1 interacts with c-Myb in a phosphorylation-dependent manner and regulates its transactivation activity.

Activity and stability of the proto-oncogene c-Myb are regulated by post-translational modifications, though the molecular mechanisms underlying such control are only partially understood. Here we describe the functional interaction of c-Myb with Pin1, an isomerase that binds to phosphorylated Ser/Thr-Pro motifs. We found that co-expression of c-Myb and Pin1 led to a net increase of c-Myb transactivation activity, both on reporter constructs as well as on an endogenous target gene. DNA-binding studies revealed that Pin1 did not increase the association of c-Myb with its response element in DNA. The increase of c-Myb transactivation activity was strictly dependent on the presence of an active catalytic center in Pin1. We provide evidence that c-Myb and Pin1 physically interacted, both upon ectopic expression of the proteins in HEK-293 cells as well as in the more physiological setting of HL60 cells, where c-Myb and Pin1 are resident proteins. By point mutating each individual Ser/Thr-Pro motif in c-Myb as well as by using deletion mutants we show that S528 in the EVES-motif was the docking site for Pin1. Mass spectrometry confirmed that S528 is phosphorylated in vivo. Finally, functional studies showed that mutation of S528 to alanine almost abolished the increase of transactivation activity by Pin1. This study reveals a new paradigm by which phosphorylation controls c-Myb function.

Identification of the prosurvival activity of nerve growth factor on cardiac myocytes.

Neurotrophins (NTs) control neuron survival and regeneration. Recent research showed that NTs possess cardiovascular actions. In this study, we investigated the hypothesis that the NT nerve growth factor (NGF) prevents cardiomyocyte apoptosis. We demonstrated that cultured rat neonatal cardiomyocytes (RNCMs) produce NGF and express its trkA (tropomyosin-related receptor A (NGF high-affinity receptor)) receptor. RNCMs given a neutralizing antibody for NGF or the trkA inhibitor K252a underwent apoptosis, thus suggesting that NGF is an endogenous prosurvival factor for cardiomyocytes. Adenovirus (Ad)-mediated NGF overexpression protected RNCMs from apoptosis induced by either hypoxia/reoxygenation or angiotensin II (AngII). Similarly, recombinant NGF inhibited AngII-induced apoptosis in isolated rat adult cardiomyocytes. Finally, in a rat model of myocardial infarction, NGF gene transfer promoted cardiomyocyte survival. In RNCMs, recombinant NGF induced trkA phosphorylation, followed by Ser473 phosphorylation and nuclear translocation of phospho-protein kinase B (Akt). In response to Akt activation, Forkhead transcription factors Foxo-3a and Foxo-1 were phosphorylated and excluded from the nucleus. The prosurvival effect of adenoviral vector carrying the human NGF gene was inhibited in vitro by K252a, LY294002 (a pan-phosphatidyl inositol 3-kinase - PI3K - inhibitor), an Akt small interfering RNA, and adenoviruses carrying a dominant negative mutant form of Akt (Ad.DN.Akt) or an Akt-resistant Foxo-3a (Ad.AAA-Foxo-3a). These results newly demonstrate the cardiac prosurvival action of NGF and provide mechanistic information on the signaling pathway, which encompasses trkA, PI3K-Akt, and Foxo.